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Fencer Intel
high 7.8

CVE-2026-31641 json

rxrpc: Fix RxGK token loading to check bounds

published 6mo ago modified 2mo ago also EUVD-2026-25534

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 6.18.23, 6.19.13, 7.0
  • Red Hat Red Hat Enterprise Linux 10 0:6.12.0-211.26.1.el10_2
  • linux Debian 14 6.19.13-1

debian advisories DEBIAN-CVE-2026-31641

  • linux-nvidia Ubuntu 26.04 LTS 7.0.0-1006.6

ubuntu advisories UBUNTU-CVE-2026-31641

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kpatch-patch-6_12_0-211_16_1 RHEL 10.2 1-6.el10_2
  • kernel RHEL 10.2 6.12.0-211.26.1.el10_2
  • rv RHEL 10.2 6.12.0-211.26.1.el10_2
  • perf RHEL 10.2 6.12.0-211.26.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.26.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.26.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.26.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.26.1.el10_2

red hat advisories RHSA-2026:55618RHSA-2026:27288

  • kernel AlmaLinux 10 6.12.0-211.26.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.26.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.26.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.26.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.26.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.26.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.26.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.26.1.el10_2

almalinux advisories ALSA-2026:27288

  • kernel Rocky Linux 10 6.12.0-211.26.1.el10_2

rocky linux advisories RLSA-2026:27288

Is CVE-2026-31641 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-31641 updated cvss 7.3

kernel: rxrpc: Fix RxGK token loading to check bounds

  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.26.1.el10_2, perf 6.12.0-211.26.1.el10_2, rtla 6.12.0-211.26.1.el10_2, python3-perf 6.12.0-211.26.1.el10_2, kernel-devel-matched 6.12.0-211.26.1.el10_2, kernel-64k-devel-matched 6.12.0-211.26.1.el10_2, +7 more Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.26.1.el10_2, kernel-64k 6.12.0-211.26.1.el10_2, kernel-core 6.12.0-211.26.1.el10_2, kernel-tools 6.12.0-211.26.1.el10_2, kernel-modules 6.12.0-211.26.1.el10_2, kernel-64k-core 6.12.0-211.26.1.el10_2, +29 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.26.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.26.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.26.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.26.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.26.1.el10_2 Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.26.1.el10_2, kernel-rt-64k 6.12.0-211.26.1.el10_2, kernel-rt-core 6.12.0-211.26.1.el10_2, kernel-rt-modules 6.12.0-211.26.1.el10_2, kernel-rt-64k-core 6.12.0-211.26.1.el10_2, kernel-rt-debug-core 6.12.0-211.26.1.el10_2, +14 more Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.26.1.el10_2, kernel-rt-core 6.12.0-211.26.1.el10_2, kernel-rt-modules 6.12.0-211.26.1.el10_2, kernel-rt-debug-core 6.12.0-211.26.1.el10_2, kernel-rt-modules-core 6.12.0-211.26.1.el10_2, kernel-rt-debug-modules 6.12.0-211.26.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:27288
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA ADP 3.1 7.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
CNA 3.1 7.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

Affected products

  • Linux Linux
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness
Technology feeds

References

Sources

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