CVE-2026-31696
Description
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix missing validation of ticket length in non-XDR key preparsing In rxrpc_preparse(), there are two paths for parsing key payloads: the XDR path (for large payloads) and the non-XDR path (for payloads <= 28 bytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly validates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR path fails to do so. This allows an unprivileged user to provide a very large ticket length. When this key is later read via rxrpc_read(), the total token size (toksize) calculation results in a value that exceeds AFSTOKEN_LENGTH_MAX, triggering a WARN_ON(). [ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc] Fix this by adding a check in the non-XDR parsing path of rxrpc_preparse() to ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX, bringing it into parity with the XDR parsing logic.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | affected | |
| debian | bullseye | affected | |
| debian | forky | fixed | 7.0.3-1 |
| debian | sid | fixed | 7.0.3-1 |
| debian | trixie | fixed | 6.12.85-1 |
| linux-kernel | affected | 6.6.136 | |
| linux-kernel | 7.1 | affected | |
| windows | affected | |
References
- https://git.kernel.org/stable/c/1fa36cf495b0023e8475d038535c05e4063211e1
- https://git.kernel.org/stable/c/4458757c020592a3094366e0fb20457383b42f92
- https://git.kernel.org/stable/c/a1be1c9ece26cea69654f28b255ff9a7906b897b
- https://git.kernel.org/stable/c/ac33733b10b484d666f97688561670afd5861383
- https://git.kernel.org/stable/c/ce383ba615339f8eaec646a166d2c2b015bb5ca0
- https://www.suse.com/security/cve/CVE-2026-31696.html
- https://security-tracker.debian.org/tracker/CVE-2026-31696
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31696
CWEs
CWE-787
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.