---
id: CVE-2026-68373
title: 'wifi: at76c50x-usb: avoid length underflow in at76_guess_freq()'
summary: |-
  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) befor…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1264b951463a00efebe1bb596499aaad620ec8af <
    cb831aff2f850f72bc5ff5ad77d0a70bb5a84061
  - >-
    Linux >= 1264b951463a00efebe1bb596499aaad620ec8af <
    4875680d1703f56afa6257ba30244f2fb44ed205
  - >-
    Linux >= 1264b951463a00efebe1bb596499aaad620ec8af <
    b406f33d234f98c8b310fdab5cbb492d85e98e49
  - >-
    Linux >= 1264b951463a00efebe1bb596499aaad620ec8af <
    e165a1d295e7e814e13b0f92c86e5d48309509ce
  - >-
    Linux >= 1264b951463a00efebe1bb596499aaad620ec8af <
    bcde7249d45f52f994a9872bedf45994472ade77
  - >-
    Linux >= 1264b951463a00efebe1bb596499aaad620ec8af <
    fb1b50ab699211e777dca5ccfb648788b6a6e519
  - >-
    Linux >= 1264b951463a00efebe1bb596499aaad620ec8af <
    f742d9c98b5c504fc9e6744eef13a721c2aea486
  - >-
    Linux >= 1264b951463a00efebe1bb596499aaad620ec8af <
    61a799ffd1e5a4fd3702d547828b7ff3d161468e
  - Linux 2.6.30
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T15:47:30.765621Z'
published: '2026-08-10'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:53:09.657Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-68373'
references:
  - url: 'https://git.kernel.org/stable/c/cb831aff2f850f72bc5ff5ad77d0a70bb5a84061'
  - url: 'https://git.kernel.org/stable/c/4875680d1703f56afa6257ba30244f2fb44ed205'
  - url: 'https://git.kernel.org/stable/c/b406f33d234f98c8b310fdab5cbb492d85e98e49'
  - url: 'https://git.kernel.org/stable/c/e165a1d295e7e814e13b0f92c86e5d48309509ce'
  - url: 'https://git.kernel.org/stable/c/bcde7249d45f52f994a9872bedf45994472ade77'
  - url: 'https://git.kernel.org/stable/c/fb1b50ab699211e777dca5ccfb648788b6a6e519'
  - url: 'https://git.kernel.org/stable/c/f742d9c98b5c504fc9e6744eef13a721c2aea486'
  - url: 'https://git.kernel.org/stable/c/61a799ffd1e5a4fd3702d547828b7ff3d161468e'
tags:
  - cve.org
epss: 0.00274
epssPercentile: 0.18487
ingestedAt: '2026-10-16T17:24:46.861Z'
---

## Overview

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.

## Affected

- `Linux >= 1264b951463a00efebe1bb596499aaad620ec8af < cb831aff2f850f72bc5ff5ad77d0a70bb5a84061`
- `Linux >= 1264b951463a00efebe1bb596499aaad620ec8af < 4875680d1703f56afa6257ba30244f2fb44ed205`
- `Linux >= 1264b951463a00efebe1bb596499aaad620ec8af < b406f33d234f98c8b310fdab5cbb492d85e98e49`
- `Linux >= 1264b951463a00efebe1bb596499aaad620ec8af < e165a1d295e7e814e13b0f92c86e5d48309509ce`
- `Linux >= 1264b951463a00efebe1bb596499aaad620ec8af < bcde7249d45f52f994a9872bedf45994472ade77`
- `Linux >= 1264b951463a00efebe1bb596499aaad620ec8af < fb1b50ab699211e777dca5ccfb648788b6a6e519`
- `Linux >= 1264b951463a00efebe1bb596499aaad620ec8af < f742d9c98b5c504fc9e6744eef13a721c2aea486`
- `Linux >= 1264b951463a00efebe1bb596499aaad620ec8af < 61a799ffd1e5a4fd3702d547828b7ff3d161468e`
- `Linux 2.6.30`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.