# CVE-2026-31657

> Vulnerability · severity: **CRITICAL** (CVSS 9.8).

## Description

In the Linux kernel, the following vulnerability has been resolved:

batman-adv: hold claim backbone gateways by reference

batadv_bla_add_claim() can replace claim->backbone_gw and drop the old
gateway's last reference while readers still follow the pointer.

The netlink claim dump path dereferences claim->backbone_gw->orig and
takes claim->backbone_gw->crc_lock without pinning the underlying
backbone gateway. batadv_bla_check_claim() still has the same naked
pointer access pattern.

Reuse batadv_bla_claim_get_backbone_gw() in both readers so they operate
on a stable gateway reference until the read-side work is complete.
This keeps the dump and claim-check paths aligned with the lifetime
rules introduced for the other BLA claim readers.

## Key facts

- **CVE ID:** CVE-2026-31657
- **Published:** 2026-04-24
- **CVSS severity:** CRITICAL
- **CVSS base score:** 9.8
- **CWE codes:** CWE-476

## Affected products

- `linux:linux_kernel`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31657

## Citation

> AI Analytics. CVE-2026-31657. Retrieved 2026-08-08 from https://api.ai-analytics.org/cve/CVE-2026-31657. Derived from NIST NVD. Licensed CC0.

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