# CVE-2026-31640

> Vulnerability · severity: **HIGH** (CVSS 7.5).

## Description

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

rxrpc: Fix use of wrong skb when comparing queued RESP challenge serial

In rxrpc_post_response(), the code should be comparing the challenge serial
number from the cached response before deciding to switch to a newer
response, but looks at the newer packet private data instead, rendering the
comparison always false.

Fix this by switching to look at the older packet.

Fix further[1] to substitute the new packet in place of the old one if
newer and also to release whichever we don't use.

## Key facts

- **CVE ID:** CVE-2026-31640
- **Published:** 2026-04-24
- **CVSS severity:** HIGH
- **CVSS base score:** 7.5
- **CWE codes:** CWE-401

## Affected products

- `linux:linux_kernel`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31640

## Citation

> AI Analytics. CVE-2026-31640. Retrieved 2026-07-24 from https://api.ai-analytics.org/cve/CVE-2026-31640. Derived from NIST NVD. Licensed CC0.

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