Skip to content
Fencer Intel
high 8.1

CVE-2026-63925 json

macsec: fix replay protection at XPN lower-PN wrap

published 3mo ago modified 15d ago also EUVD-2026-45698

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits
0
none known

Summary

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

macsec: fix replay protection at XPN lower-PN wrap

In macsec_post_decrypt(), when pn is U32_MAX, pn + 1 overflows u32 to 0 and the first branch never fires. If next_pn_halves.lower is also in the upper half, pn_same_half(pn, lower) is true and the XPN else-if does not fire either, leaving next_pn_halves unchanged. An attacker that captures the legitimate frame carrying pn == 0xFFFFFFFF on an XPN association can then replay it indefinitely, since lowest_pn never rises above the captured pn and macsec_decrypt() reconstructs the same IV.

Extend the XPN else-if to also fire when pn + 1 wraps to 0, so receipt of pn == U32_MAX advances next_pn_halves to (upper + 1, 0).

Patch / fix

  • Linux Linux 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.94-1
  • linux Debian 14 7.0.12-1

debian advisories DEBIAN-CVE-2026-63925

  • linux Ubuntu 22.04 LTS 5.15.0-198.208
  • linux Ubuntu 24.04 LTS 6.8.0-146.146
  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1117.124
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1066.69
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1118.128
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1070.78

ubuntu advisories UBUNTU-CVE-2026-63925

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

  • kernel RHEL 9 5.14.0-687.57.1.el9_8
  • rv RHEL 9 5.14.0-687.57.1.el9_8
  • perf RHEL 9 5.14.0-687.57.1.el9_8
  • rtla RHEL 9 5.14.0-687.57.1.el9_8
  • libperf RHEL 9 5.14.0-687.57.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.57.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.57.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.57.1.el9_8

red hat advisories RHSA-2026:81552RHSA-2026:81406

  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.81.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.81.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1.150700.17.45.1

suse advisories SUSE-SU-2026:4254-1SUSE-SU-2026:23887-1SUSE-SU-2026:23902-1SUSE-SU-2026:23897-1SUSE-SU-2026:23881-1SUSE-SU-2026:4120-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.38.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.38.1

opensuse advisories openSUSE-SU-2026:21910-1

  • kernel AlmaLinux 10 6.12.0-211.65.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.65.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.65.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.65.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.65.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.65.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.65.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.65.1.el10_2

almalinux advisories ALSA-2026:81406ALSA-2026:81552

  • kernel Rocky Linux 10 6.12.0-211.65.1.el10_2
  • kernel Rocky Linux 9 5.14.0-687.57.1.el9_8

rocky linux advisories RLSA-2026:81406RLSA-2026:81552

Is CVE-2026-63925 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.

Check with Fencer

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-2026-63925 updated cvss 8.1

kernel: macsec: fix replay protection at XPN lower-PN wrap

  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available
  • Red Hat Enterprise Linux kernel-modules-internal 6.12.0-211.65.1.el10_2
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.57.1.el9_8, perf 5.14.0-687.57.1.el9_8, rtla 5.14.0-687.57.1.el9_8, python3-perf 5.14.0-687.57.1.el9_8, kernel-devel-matched 5.14.0-687.57.1.el9_8, kernel-64k-devel-matched 5.14.0-687.57.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:81552
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.65.1.el10_2, perf 6.12.0-211.65.1.el10_2, rtla 6.12.0-211.65.1.el10_2, python3-perf 6.12.0-211.65.1.el10_2, kernel-devel-matched 6.12.0-211.65.1.el10_2, kernel-64k-devel-matched 6.12.0-211.65.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.57.1.el9_8, kernel-64k 5.14.0-687.57.1.el9_8, kernel-core 5.14.0-687.57.1.el9_8, kernel-tools 5.14.0-687.57.1.el9_8, kernel-modules 5.14.0-687.57.1.el9_8, kernel-64k-core 5.14.0-687.57.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:81552
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.65.1.el10_2, kernel-64k 6.12.0-211.65.1.el10_2, kernel-core 6.12.0-211.65.1.el10_2, kernel-tools 6.12.0-211.65.1.el10_2, kernel-modules 6.12.0-211.65.1.el10_2, kernel-64k-core 6.12.0-211.65.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.57.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.57.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.57.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.57.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.57.1.el9_8
    fixed: vendor fix RHSA-2026:81552
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.65.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.65.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.65.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.65.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.65.1.el10_2 Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal 6.12.0-211.65.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.65.1.el10_2
    fixed: vendor fix RHSA-2026:81406
show 5 more
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.57.1.el9_8, kernel-rt-64k 5.14.0-687.57.1.el9_8, kernel-rt-core 5.14.0-687.57.1.el9_8, kernel-rt-modules 5.14.0-687.57.1.el9_8, kernel-rt-64k-core 5.14.0-687.57.1.el9_8, kernel-rt-debug-core 5.14.0-687.57.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:81552
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.65.1.el10_2, kernel-rt-64k 6.12.0-211.65.1.el10_2, kernel-rt-core 6.12.0-211.65.1.el10_2, kernel-rt-modules 6.12.0-211.65.1.el10_2, kernel-rt-64k-core 6.12.0-211.65.1.el10_2, kernel-rt-debug-core 6.12.0-211.65.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.57.1.el9_8, kernel-rt-core 5.14.0-687.57.1.el9_8, kernel-rt-modules 5.14.0-687.57.1.el9_8, kernel-rt-debug-core 5.14.0-687.57.1.el9_8, kernel-rt-modules-core 5.14.0-687.57.1.el9_8, kernel-rt-debug-modules 5.14.0-687.57.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:81552
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.65.1.el10_2, kernel-rt-core 6.12.0-211.65.1.el10_2, kernel-rt-modules 6.12.0-211.65.1.el10_2, kernel-rt-debug-core 6.12.0-211.65.1.el10_2, kernel-rt-modules-core 6.12.0-211.65.1.el10_2, kernel-rt-debug-modules 6.12.0-211.65.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:81406
  • 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
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
26d ago

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.