CVE-2026-31641: Linux kernel · rxrpc: Fix RxGK token loading to check bounds
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 12 Nov 2026, 00:34 UTC
Sources agree
| CNA (Linux) | CVSS 3.1 | 7.8 |
|---|---|---|
| ADP (redhat-SADP) | CVSS 3.1 | 7.3 |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 24 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.
Description
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix RxGK token loading to check bounds rxrpc_preparse_xdr_yfs_rxgk() reads the raw key length and ticket length from the XDR token as u32 values and passes each through round_up(x, 4) before using the rounded value for validation and allocation. When the raw length is >= 0xfffffffd, round_up() wraps to 0, so the bounds check and kzalloc both use 0 while the subsequent memcpy still copies the original ~4 GiB value, producing a heap buffer overflow reachable from an unprivileged add_key() call. Fix this by: (1) Rejecting raw key lengths above AFSTOKEN_GK_KEY_MAX and raw ticket lengths above AFSTOKEN_GK_TOKEN_MAX before rounding, consistent with the caps that the RxKAD path already enforces via AFSTOKEN_RK_TIX_MAX. (2) Sizing the flexible-array allocation from the validated raw key length via struct_size_t() instead of the rounded value. (3) Caching the raw lengths so that the later field assignments and memcpy calls do not re-read from the token, eliminating a class of TOCTOU re-parse. The control path (valid token with lengths within bounds) is unaffected.
References
- git.kernel.org/stable/c/3e04596cba8a86cbff9c3f4bf0a524a3a488773c (opens in a new tab)
- git.kernel.org/stable/c/49875b360c2b83a3c226e189c502e501d83e6445 (opens in a new tab)
- git.kernel.org/stable/c/d179a868dd755b0cfcf7582e00943d702b9943b8 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-31641 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2461548 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31641.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:27288 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:55618 (opens in a new tab)