Short answer: Wi-Fi can detect movement through walls, but it does not "see" you like a camera. Every Wi-Fi link measures how the radio channel changes (channel state information, or CSI). When a person moves, those measurements change. Routers from Comcast and Plume already turn this into opt-in motion alerts Xfinity support: WiFi Motion FAQs (vendor page, updated 30 Aug 2026) Plume blog: Plume Motion (vendor page, first published Jan 2020, checked 10 Oct 2026). Since 26 September 2025 the IEEE has a published standard for it, IEEE 802.11bf "WLAN sensing" IEEE SA: IEEE 802.11bf-2025, published 26 Sep 2025.
The research is further ahead than the products. Researchers have shown three things in experiments. MIT estimated body poses through a wall using a custom radio, not a Wi-Fi router Zhao et al., Through-Wall Human Pose Estimation Using Radio Signals, CVPR 2018. A team at UChicago and UCSB tracked people room by room from outside a building with one smartphone Zhu et al., Et Tu Alexa?, NDSS 2020 (arXiv v4, 11 Jan 2020). KIT identified 161 trained participants with 99.5% accuracy from Wi-Fi beamforming data Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF). All three ran in controlled studies, and the KIT and MIT systems had to be trained on the people or scenes first.
The 2026 "Wi-Fi tracks you through walls" headlines mostly recycled two older papers. One was a 2022 Carnegie Mellon preprint that did not test through walls at all Geng, Huang & De la Torre, DensePose From WiFi, arXiv:2301.00250 (31 Dec 2022). The other was the October 2025 KIT paper KITopen record: BFId, CCS 2025 (13 Oct 2025). Nothing reviewed here shows a stranger using your home Wi-Fi to identify you without that preparation.
At a glance: what is real, what is lab-only, and what is hype
| Claim | Status (Oct 2026) | What it actually took | Source |
|---|---|---|---|
| A home router can alert you to motion in your home | Deployed | Opt-in feature. Uses the gateway plus up to five stationary devices you choose (Xfinity). | Xfinity, Plume (vendor claims) |
| Wi-Fi sensing has an IEEE standard | Deployed (standard only) | IEEE 802.11bf-2025, approved 28 May 2025, published 26 Sep 2025. Which products support it was not checked here. | IEEE SA |
| Someone outside can tell whether, and in which room, people are moving | Lab-demonstrated | One smartphone sniffer outside; existing Wi-Fi devices inside act as "anchors"; tested in 11 offices and homes (2020). | NDSS 2020 paper |
| Radio signals can estimate a body pose through a wall | Lab-demonstrated | A custom FMCW radio with antenna arrays, not Wi-Fi; trained with a camera; works up to 40 feet (2018). | MIT CSAIL, CVPR 2018 |
| Off-the-shelf Wi-Fi can map body shape (DensePose) | Lab-demonstrated | 3 transmit and 3 receive antennas, 8 people, same rooms used for training; no wall tested; not peer reviewed (2022). | CMU arXiv preprint |
| Wi-Fi can identify who you are | Lab-demonstrated | 161 enrolled participants in a controlled walkway, tight clothing rules, model trained on each person first (2025). | KIT, CCS 2025 |
| A stranger can identify an unknown person through walls with your router | Not shown / speculative | No study reviewed here shows this without first training on that person. | — |
| A drone can locate the Wi-Fi devices inside a building | Lab-demonstrated | Drone plus about $20 of parts; locates devices, not bodies, to about 1 metre (2022). | Univ. of Waterloo |
What is Wi-Fi sensing, and how can Wi-Fi detect movement?
Wi-Fi sensing means using ordinary Wi-Fi transmissions to learn something about the space they pass through: whether someone is there, whether they are moving, sometimes how they are moving. It works because a radio link is never just a straight line. Signals bounce off walls, furniture and bodies, and a person walking through the space changes that pattern. KIT's researchers put it simply: a human in the signal's path causes more interference than an empty room Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF).
Two kinds of measurement come up in the research and the 2026 news:
- Channel state information (CSI). A receiver estimates CSI for each transmission. CMU's paper describes it as the ratio between the transmitted and received signal wave, recorded across many subcarrier frequencies and antenna pairs Geng, Huang & De la Torre, DensePose From WiFi, arXiv:2301.00250 (31 Dec 2022). Most CSI research has used old or specialist network cards. In the studies KIT reviewed, the Intel 5300, released in 2008, was the most common one Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF).
- Beamforming feedback information (BFI). When a modern router "beamforms", connected devices send back a compressed summary of the channel. KIT's paper points out that this feedback is sent unencrypted, so it "can be easily accessed" by any Wi-Fi card in monitor mode within range Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF).
The standard. IEEE 802.11bf, "Enhancements for Wireless LAN Sensing", is listed by the IEEE Standards Association as an Active Standard, approved on 28 May 2025 and published on 26 September 2025. It amends the 802.11 MAC and PHY to support sensing in license-exempt bands between 1 GHz and 7.125 GHz and above 45 GHz IEEE SA: IEEE 802.11bf-2025, published 26 Sep 2025. A published standard is not the same as products in your home: we did not find a primary source listing devices that implement it, so we leave that blank.
"Wi-Fi tracking" can also mean two other things. One is following your phone by its Wi-Fi broadcasts, the way shops count visitors; see section 6. The other is the network owner seeing which websites you visit; see the FAQ. Those are different technologies with different defences.
Can Wi-Fi see through walls? What the research actually showed
Yes, radio at Wi-Fi frequencies passes through most interior walls, and several research teams have used that to sense people in another room. But each result comes with conditions that the headlines leave out. Here is what the papers themselves report:
| Study | Hardware | Through a wall? | Training needed | Reported result |
|---|---|---|---|---|
| MIT CSAIL, RF-Pose (CVPR 2018) Zhao et al., Through-Wall Human Pose Estimation Using Radio Signals, CVPR 2018 | A custom radio with vertical and horizontal antenna arrays that sends an FMCW signal "1000 times lower power than WiFi"; works up to 40 feet | Yes: tested on through-wall scenes | Yes. A camera-based model supervised training; data from 50 campus environments | Pose AP 62.4 on visible scenes and 58.1 through walls (the camera system "fails completely" there). Identified 100 people from walking with over 83% accuracy |
| UChicago and UCSB, "Et Tu Alexa?" (NDSS 2020) Zhu et al., Et Tu Alexa?, NDSS 2020 (arXiv v4, 11 Jan 2020) | One commodity smartphone with a single antenna, passively sniffing outside the property | Yes: the sniffer was outside, in 11 offices, apartments and houses | No training on the people. It uses existing Wi-Fi devices inside as "anchors" | Detected motion 86.8% of the time with 1 anchor per room, up to 99.988% with 4; false positives under 3% with 1 anchor. Detects presence and room, not identity |
| Carnegie Mellon, "DensePose From WiFi" (arXiv, Dec 2022) Geng, Huang & De la Torre, DensePose From WiFi, arXiv:2301.00250 (31 Dec 2022) | 3 transmitting and 3 receiving antennas at 2.4 GHz; the authors note routers like the TP-Link AC1750 cost about $30 | No wall was tested. Data came from a lab office and a classroom | Yes. Labels came from a camera-based model; 8 people in 16 layouts | Person detection AP 43.5 (AP@50 87.2) in trained layouts; AP fell to 27.3 in an unseen layout |
| KIT, BFId (ACM CCS, Oct 2025) Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF) | Two TP-Link Archer BE800 routers on 6 GHz; Intel AX210 cards as receivers | Partly: one of four viewpoints was "in the neighboring room", with slightly lower accuracy | Yes. Each person was enrolled first (80:20 train/test split) | 99.5% ± 0.38 identification of 161 people from beamforming feedback; 82.4% ± 0.62 from CSI for 170 people |
| Univ. of Waterloo, Wi-Peep (MobiCom 2022) University of Waterloo news (3 Nov 2022) | A store-bought drone and about $20 of parts | Yes: it flies outside a building | None | Locates Wi-Fi devices to within about a metre by timing their automatic replies. It finds devices, not bodies |
What these studies do not show. None of them shows a stranger turning an ordinary home router into a camera. RF-Pose did not use a Wi-Fi router at all, and its authors list limits: bodies block each other, and range depends on transmit power Zhao et al., Through-Wall Human Pose Estimation Using Radio Signals, CVPR 2018. CMU found the model "biased" on rare poses and weaker with three or more people. It called deployment in an untrained layout "a very challenging problem" Geng, Huang & De la Torre, DensePose From WiFi, arXiv:2301.00250 (31 Dec 2022). KIT recorded participants walking a set path, told them not to wear baggy clothes, skirts, dresses or heeled shoes, and says this "may be overestimating" what BFI can identify Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF).
What they do show. Detecting whether someone is moving in a room is easy, works through walls and needs no training on the person. The UChicago and UCSB attack did it from outside with one phone, "without compromising any WiFi network, data packets, or devices" Zhu et al., Et Tu Alexa?, NDSS 2020 (arXiv v4, 11 Jan 2020). Identifying a person is possible in a controlled study once the system has been trained on that person Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF) Zhao et al., Through-Wall Human Pose Estimation Using Radio Signals, CVPR 2018.
What is behind the 2026 "Wi-Fi tracks you through walls" headlines?
Most of the 2026 coverage rewrote research that was already public:
- "Scientists Show That Routers Can Be Used To Track Your Movements Through Walls" (BGR, 20 May 2026). The article describes Carnegie Mellon work using three routers and three receivers, and notes the study "has not been peer-reviewed yet" BGR (20 May 2026). The paper it links is the CMU preprint from 31 December 2022 Geng, Huang & De la Torre, DensePose From WiFi, arXiv:2301.00250 (31 Dec 2022). Our reading of that preprint: it never tests a wall. Its data came from a lab office and a classroom, with cameras recording at the same time to produce training labels.
- KIT's "invisible mass surveillance" warning (SciTechDaily, 3 Feb 2026; ScienceDaily, 12 Aug 2026). Both describe the BFId study: 197 participants, "almost 100% accuracy", and identification in "a few seconds" once the model is trained SciTechDaily (3 Feb 2026) ScienceDaily (12 Aug 2026). The paper was presented at ACM CCS in Taipei in October 2025, and KIT's own press release is dated 8 October 2025 KIT press release 069/2025 (8 Oct 2025). Neither 2026 article says the method works through walls. The paper's 99.5% figure comes from 161 enrolled people in a controlled walkway, not from strangers on a street Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF).
The KIT finding still matters, for a reason the headlines mostly skipped. The data it uses, beamforming feedback, is broadcast unencrypted by every device that takes part in beamforming. An attacker "does not need to have access to the WiFi access point or its network" to record it, and lowering how often it is sent was "ineffective" as a defence in their tests Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF). The researchers' main request is that 802.11bf "should strongly consider adding effective privacy protection, or abandon beamforming entirely" Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF).
What Wi-Fi motion sensing is shipping in homes today?
Commercial products use the simplest version of the technology: motion yes or no, in an area between your router and a device. All descriptions below are vendor claims from the companies selling the feature, unless marked otherwise.
| Product | What it does (vendor claim) | Default | How it is controlled | Source |
|---|---|---|---|---|
| Xfinity WiFi Motion (Comcast) | Sensing areas are "formed between the Xfinity WiFi equipment and up to five WiFi connected devices". It "does not use cameras, capture images or video, or record audio". By default it detects "even small amounts of movement", including small pets. | Off. Xfinity calls it "an opt-in feature". | Xfinity app: Home tab, WiFi Motion status, gear icon, Remove WiFi Motion. Needs a compatible leased gateway. | Xfinity support: WiFi Motion FAQs (vendor page, updated 30 Aug 2026) Xfinity support: Using WiFi Motion (vendor page, updated 30 Aug 2026) |
| Plume Sense / Plume Motion (HomePass) | Turns SuperPods and other connected devices into "camera-free motion sensors". Shows 7 days of movement history, with a pet mode. The datasheet says "Detect activity even in bathrooms and bedrooms". | Opt-in: Plume calls Sense "completely opt-in". | HomePass app. You choose or remove the devices that act as sensors. Sold through internet providers. | Plume blog: Plume Motion (vendor page, first published Jan 2020, checked 10 Oct 2026) Plume Sense datasheet (vendor document, 2021) |
| Linksys Aware (2019) | Reported at launch as motion sensing through Velop mesh Wi-Fi, with pet filtering and up to 60 days of history, at $3 a month after a free trial. | Subscription | Linksys app. Linksys's own Aware support pages now redirect, so its current status is not confirmed here. | 9to5Mac (8 Oct 2019) (press report) |
What Comcast says about privacy. According to Comcast's FAQ, the company "does not monitor the motion and/or notifications generated by the service". It also says Comcast "may be required to disclose information generated by WiFi Motion" in response to valid legal process Xfinity support: WiFi Motion FAQs (vendor page, updated 30 Aug 2026). BleepingComputer quoted Comcast saying the feature "is designed to detect motion, not identify specific people, and does not track the exact location of movement" BleepingComputer (18 Aug 2026). Comcast announced Xfinity Shield, which bundles WiFi Motion, on 18 August 2026 BleepingComputer (18 Aug 2026).
What Plume says. "There is no specific recognition of people", and "only you are able to see the levels of motion" Plume blog: Plume Motion (vendor page, first published Jan 2020, checked 10 Oct 2026).
Our assessment: these features see what any Wi-Fi sensing system sees. The difference is who holds the data and on what terms. Check the account owner and the provider's legal-process terms before you treat it as a private sensor.
Who can track movement with your Wi-Fi: you, your ISP, or a stranger?
Separate four situations, because the risk is very different in each:
- You, with a feature you turned on. This is the commercial case above. The account holder chooses the sensing devices and sees the alerts Xfinity support: Using WiFi Motion (vendor page, updated 30 Aug 2026).
- Your internet provider. With Xfinity, the data comes from equipment Comcast leases to you. Comcast says it does not monitor the alerts, but it may have to disclose them under legal process Xfinity support: WiFi Motion FAQs (vendor page, updated 30 Aug 2026). This is a vendor statement we cannot audit.
- Someone else in the household who controls the router or ISP app. Xfinity limits the Home tab to Primary, Manager and Member Xfinity ID users Xfinity support: Using WiFi Motion (vendor page, updated 30 Aug 2026). In a shared home or an abusive relationship, check who has those roles.
- An outsider, without your password. The research says this is possible for motion. The NDSS 2020 attack needed no access to the network: one phone outside measured signals from devices inside and placed movement in individual rooms Zhu et al., Et Tu Alexa?, NDSS 2020 (arXiv v4, 11 Jan 2020). BFI can also be recorded passively by a receiver that is not on your network, though the KIT attacker still needs labelled training data for each person it wants to recognise Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF). Waterloo's Wi-Peep located the devices inside a building from a drone, because devices reply to contact attempts "from any device within range" even on password-protected networks University of Waterloo news (3 Nov 2022).
Turning off your own phone does not opt you out. Device-free sensing measures how your body disturbs other devices' signals. KIT's Thorsten Strufe: "It's sufficient that other WiFi devices in your surroundings are active" KIT press release 069/2025 (8 Oct 2025).
What remains speculative. We found no published demonstration of an outsider using a home's existing Wi-Fi to identify a specific, untrained person through a wall, or to produce camera-like images of them. If you see that claim, ask for the paper.
How is this different from Wi-Fi tracking in shops (MAC addresses and probe requests)?
Shop and venue "Wi-Fi tracking" follows your device, not your body. Phones send "Probe Request" frames to discover networks. Analytics sensors collect these and use them to estimate occupancy, foot traffic and time spent in an area, according to Spain's data protection authority (AEPD) AEPD et al., Wi-Fi tracking guidance (PDF, May 2024).
| Wi-Fi sensing (CSI / BFI) | Wi-Fi device tracking (probe requests, MAC) | |
|---|---|---|
| What is measured | Changes in the radio channel caused by bodies | Frames your phone or laptop transmits |
| Do you need to carry a device? | No. Other devices' signals are enough KIT press release 069/2025 (8 Oct 2025) | Yes. It tracks the device |
| Typical output | Motion yes/no, room, sometimes pose or identity in lab studies | Device counts, dwell time, repeat visits AEPD et al., Wi-Fi tracking guidance (PDF, May 2024) |
| Main defence | Few consumer options; turn off router sensing features | MAC randomization, Wi-Fi off when not needed |
MAC randomization helps, but it is not complete.
- Apple. Apple devices "use a randomized Media Access Control address (MAC address) when performing Wi-Fi scans when not associated", but scans for a preferred network "aren't randomized" Apple Platform Security: Wi-Fi privacy (checked 10 Oct 2026). For each network you join, iOS 18 and macOS Sequoia offer Off, Fixed or Rotating private addresses, and Rotating changes "every 2 weeks" Apple Support: private Wi-Fi addresses (checked 10 Oct 2026).
- Android. Since Android 8.0, devices "use randomized MAC addresses when probing for new networks while not associated with a network" Android Open Source Project: MAC randomization (checked 10 Oct 2026). Since Android 10, "the framework uses a randomized MAC address by default" when connecting, persistent per network, with non-persistent options from Android 12 AOSP: MAC randomization behavior (checked 10 Oct 2026).
- The limits. The AEPD notes that randomization is not standardised, that the address stays fixed for the whole of a connection, and that an estimated 5% to 10% of devices do not randomize at all. It adds that many techniques can still single out a device "en un elevado porcentaje de casos" (in a high percentage of cases) by combining probe-request contents and statistical patterns AEPD et al., Wi-Fi tracking guidance (PDF, May 2024).
To look up which manufacturer a hardware MAC address belongs to, use Max Intel's MAC Address Lookup. A randomized address will not match a real vendor.
Is Wi-Fi tracking legal? What GDPR and the AEPD say
In the EU, Wi-Fi tracking of people's devices can be processing of personal data under the GDPR. On 7 May 2024, Spain's AEPD, together with the Catalan, Basque and Andalusian authorities, published guidance for organisations that use it AEPD press release (7 May 2024). Its main points:
- A data protection impact assessment is generally considered mandatory, and is recommended even where the organisation is unsure AEPD press release (7 May 2024).
- People must get "una información clara y accesible" (clear, accessible information), for example signs, information panels or voice notices AEPD press release (7 May 2024).
- Data should be anonymised and aggregated "justo después de la recogida" (right after collection). The tracked area should be limited, and a device should not get the same identifier on repeat visits AEPD press release (7 May 2024).
- Walls do not contain the signal. A system in one building may pick up devices "en hogares o domicilios privados que estén detrás de un muro" (in private homes behind a wall). The authorities say that would be "no un riesgo, sino un incumplimiento" (not a risk, but a breach) of the lawfulness principle AEPD et al., Wi-Fi tracking guidance (PDF, May 2024).
The gap. The AEPD guidance is about tracking devices through their transmissions. We found no AEPD guidance specifically on device-free CSI or BFI body sensing. The KIT team treated its gait recordings as biometric data, a special category under Article 9 GDPR, told participants in writing that such data would be recorded, and had ethics approval Todt, Morsbach & Strufe, BFId, ACM CCS 2025 (paper PDF). Outside the EU the rules differ. We have not assessed US federal or state law here, and this page is not legal advice.
What can you realistically do about Wi-Fi sensing and tracking?
Most of what you can control is on your own network and devices:
- Check your ISP app for motion features. With Xfinity, look for the WiFi Motion tile on the Home tab. To turn it off, open the gear icon and choose Remove WiFi Motion Xfinity support: Using WiFi Motion (vendor page, updated 30 Aug 2026). With a Plume or HomePass system, check Sense, which is opt-in and lets you remove sensing devices Plume blog: Plume Motion (vendor page, first published Jan 2020, checked 10 Oct 2026). Other providers that resell Plume may brand it differently.
- Check who can open the router app. Remove old household members and shared logins. On Xfinity, the Home tab is limited to Primary, Manager and Member users Xfinity support: Using WiFi Motion (vendor page, updated 30 Aug 2026).
- Keep private Wi-Fi addresses on. On iPhone, iPad and Mac, Apple recommends leaving the feature on, and Rotating is the default for open or weakly secured networks Apple Support: private Wi-Fi addresses (checked 10 Oct 2026). On Android 10 and later, randomization is on by default for each network AOSP: MAC randomization behavior (checked 10 Oct 2026). This limits shop-style device tracking, not body sensing.
- Turn Wi-Fi off on your phone when you don't need it in places with venue analytics. A radio that is off sends no probe requests. This does not stop device-free sensing by other devices KIT press release 069/2025 (8 Oct 2025).
- For the "websites visited" worry, encrypt DNS. Without DNS over HTTPS, "someone lurking on public Wi-Fi, your ISP, or anyone else on your local network" can see which site you are about to visit Mozilla Support: DNS over HTTPS (checked 10 Oct 2026).
- Be realistic about outsiders. Researchers' defences against outside sensing are still experimental. The NDSS 2020 team's router-side obfuscation cut the attacker's detection rate to 47% while pushing false positives to 50% Zhu et al., Et Tu Alexa?, NDSS 2020 (arXiv v4, 11 Jan 2020). As of 10 October 2026 we found no consumer router that advertises this, so we leave it as research.
For broader threat modelling, see the OSINT OpSec guide. For other radio-based surveillance, see IMSI catchers and Stingrays and Ring and Amazon Sidewalk OPSEC. To look up networks and cell towers, use Wireless OSINT.
Frequently Asked Questions
Can Wi-Fi see through walls?
Wi-Fi signals pass through most interior walls, so Wi-Fi can detect that someone is moving in another room. It does not produce camera-like images. In research, MIT estimated body poses through walls in 2018, but with a custom radio rather than a Wi-Fi router and after camera-supervised training. A 2020 study detected and placed motion room by room from outside a building using one smartphone.
Can Wi-Fi track movement in my home?
Yes, and some internet providers sell it as a feature. Xfinity WiFi Motion and Plume Sense send motion alerts based on changes in Wi-Fi signals between the router and devices you choose. Both companies describe these features as opt-in. They detect that something moved in a sensing area, not who it was.
Can Wi-Fi track and identify people?
In controlled studies, yes. A KIT study presented in October 2025 identified 161 enrolled participants with 99.5 percent accuracy from Wi-Fi beamforming feedback. The model was trained on each person first, people walked a set path, and loose clothing was not allowed. No study reviewed here identifies untrained strangers through walls.
What is CSI Wi-Fi tracking?
CSI means channel state information: the detailed measurements a Wi-Fi receiver makes of how the signal changed between transmitter and receiver across many frequencies and antennas. Movement changes CSI, so it can be used to detect motion, estimate poses or recognise gait. Research usually needs special network cards or firmware to read CSI. Newer work uses beamforming feedback, which devices broadcast unencrypted.
Does Xfinity track you with Wi-Fi?
Xfinity WiFi Motion is an opt-in feature that uses your Xfinity gateway and up to five WiFi-connected devices to detect motion. Comcast says it does not use cameras or record audio, does not identify specific people, and does not monitor the alerts. It also says it may be required to disclose WiFi Motion information under valid legal process. You can remove it in the Xfinity app.
Can a neighbour or stranger use my Wi-Fi to watch me?
Researchers have shown that an outsider can detect movement and which room it is in, using one smartphone outside the building and the signals from Wi-Fi devices inside, without knowing your password. That shows presence and motion, not a picture or your identity. Identifying a person in research required training on that person first.
Is Wi-Fi tracking legal under GDPR?
Tracking devices through their Wi-Fi signals can be personal data processing under the GDPR. In May 2024 the Spanish AEPD and three regional authorities said an impact assessment is generally mandatory and called for clear signage. They also called for anonymisation right after collection and no persistent identifier across visits. Their guidance covers device tracking, not body sensing.
Can the Wi-Fi owner see what websites I visit?
Often they can see which sites you look up. Mozilla says that without DNS over HTTPS, someone on public Wi-Fi, your ISP or anyone else on your local network can see which website you are about to access. Turning on DNS over HTTPS in your browser hides those lookups from the local network. This is separate from Wi-Fi motion sensing.