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

> An integer overflow in the batman-adv kernel module allows heap buffer overflows, potentially leading to code execution or denial of service.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Apr 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-83870, BELL-CVE-2026-31659, DEBIAN-CVE-2026-31659, GHSA-8jfv-frvf-4g4v, ROOT-OS-DEBIAN-11-CVE-2026-31659, ROOT-OS-DEBIAN-12-CVE-2026-31659, ROOT-OS-UBUNTU-2204-CVE-2026-31659, ROOT-OS-UBUNTU-2404-CVE-2026-31659, UBUNTU-CVE-2026-31659

## What is CVE-2026-31659?

CVE-2026-31659 is a critical vulnerability in Linux kernel, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-31659?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31659?

Apply the vendor's patch.

## Is CVE-2026-31659 being exploited?

There is no known exploitation of CVE-2026-31659 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31659 and fix it if it is affected.

What it is: CVE-2026-31659 is a critical vulnerability in Linux kernel, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-31659 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-31659/ (Markdown: https://insights.sbomify.com/CVE-2026-31659/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31659
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31659
- OSV: https://osv.dev/vulnerability/CVE-2026-31659

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31659/
Summaries are generated and may contain mistakes; the official description above is the record.