# CVE-2026-68373: wifi: at76c50x-usb: avoid length underflow in at76_guess_freq()

> An integer underflow in the at76c50x-usb WiFi driver allows out-of-bounds reads during scanning, potentially causing information disclosure or system crashes.

- **Severity:** High 8.1 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-68373, DEBIAN-CVE-2026-68373, GHSA-rhfx-w25m-wcjf, UBUNTU-CVE-2026-68373

## What is CVE-2026-68373?

CVE-2026-68373 is a high-severity vulnerability in Linux, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-68373?


## How do I fix CVE-2026-68373?

Apply the vendor's patch.

## Is CVE-2026-68373 being exploited?

There is no known exploitation of CVE-2026-68373 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68373 and fix it if it is affected.

What it is: CVE-2026-68373 is a high-severity vulnerability in Linux, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-68373 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-68373/ (Markdown: https://insights.sbomify.com/CVE-2026-68373/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68373
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68373
- OSV: https://osv.dev/vulnerability/CVE-2026-68373

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68373/
Summaries are generated and may contain mistakes; the official description above is the record.