# CVE-2025-68799: caif: fix integer underflow in cffrml_receive()

> An attacker can cause kernel instability and potential information disclosure via integer underflow in the CAIF protocol when FCS is disabled.

- **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:** 13 Jan 2026
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-74327, BELL-CVE-2025-68799, DEBIAN-CVE-2025-68799, GHSA-pxpq-p89v-xx8g, ROOT-OS-DEBIAN-11-CVE-2025-68799, ROOT-OS-DEBIAN-12-CVE-2025-68799, ROOT-OS-DEBIAN-13-CVE-2025-68799, ROOT-OS-UBUNTU-2204-CVE-2025-68799, ROOT-OS-UBUNTU-2404-CVE-2025-68799, UBUNTU-CVE-2025-68799

## What is CVE-2025-68799?

CVE-2025-68799 is a high-severity vulnerability in Linux, published on 13 Jan 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:

caif: fix integer underflow in cffrml_receive()

The cffrml_receive() function extracts a length field from the packet
header and, when FCS is disabled, subtracts 2 from this length without
validating that len >= 2.

If an attacker sends a malicious packet with a length field of 0 or 1
to an interface with FCS disabled, the subtraction causes an integer
underflow.

This can lead to memory exhaustion and kernel instability, potential
information disclosure if padding contains uninitialized kernel memory.

Fix this by validating that len >= 2 before performing the subtraction.

## Which versions are affected by CVE-2025-68799?


## How do I fix CVE-2025-68799?

Apply the vendor's patch.

## Is CVE-2025-68799 being exploited?

There is no known exploitation of CVE-2025-68799 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68799 and fix it if it is affected.

What it is: CVE-2025-68799 is a high-severity vulnerability in Linux, published on 13 Jan 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-2025-68799 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-2025-68799/ (Markdown: https://insights.sbomify.com/CVE-2025-68799/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68799
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68799
- OSV: https://osv.dev/vulnerability/CVE-2025-68799

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68799/
Summaries are generated and may contain mistakes; the official description above is the record.