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Fencer Vulns
high 7.8

CVE-2025-21893 json

keys: Fix UAF in key_put()

published 2025-03-31 19 mo ago modified 2026-08-05 3 mo ago also EUVD-2025-8870

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

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

keys: Fix UAF in key_put()

Once a key's reference count has been reduced to 0, the garbage collector thread may destroy it at any time and so key_put() is not allowed to touch the key after that point. The most key_put() is normally allowed to do is to touch key_gc_work as that's a static global variable.

However, in an effort to speed up the reclamation of quota, this is now done in key_put() once the key's usage is reduced to 0 - but now the code is looking at the key after the deadline, which is forbidden.

Fix this by using a flag to indicate that a key can be gc'd now rather than looking at the key's refcount in the garbage collector.

Patch / fix

  • Linux Linux 6.12.21, 6.13.9, 6.14
  • linux Debian 14, Debian 13 6.12.21-1

debian advisories DEBIAN-CVE-2025-21893

  • linux-gcp-6.11 Ubuntu 24.04 LTS 6.11.0-1016.16~24.04.1
  • linux-hwe-6.11 Ubuntu 24.04 LTS 6.11.0-28.28~24.04.1
  • linux-oem-6.11 Ubuntu 24.04 LTS 6.11.0-1024.24
  • linux-azure-6.11 Ubuntu 24.04 LTS 6.11.0-1018.18~24.04.1
  • linux-nvidia-6.11 Ubuntu 24.04 LTS 6.11.0-1012.12
  • linux-lowlatency-hwe-6.11 Ubuntu 24.04 LTS 6.11.0-1015.16~24.04.2

ubuntu advisories UBUNTU-CVE-2025-21893

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 10.0 6.12.0-55.17.1.el10_0
  • rv RHEL 10.0 6.12.0-55.17.1.el10_0
  • perf RHEL 10.0 6.12.0-55.17.1.el10_0
  • rtla RHEL 10.0 6.12.0-55.17.1.el10_0
  • libperf RHEL 10.0 6.12.0-55.17.1.el10_0
  • kernel-rt RHEL 10.0 6.12.0-55.17.1.el10_0
  • kernel-64k RHEL 10.0 6.12.0-55.17.1.el10_0
  • kernel-core RHEL 10.0 6.12.0-55.17.1.el10_0

red hat advisories RHSA-2025:9079

  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-syms-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-source-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.3.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.3.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1

suse advisories SUSE-SU-2025:01967-1SUSE-SU-2025:01951-1

  • kernel Rocky Linux 10 6.12.0-55.17.1.el10_0

rocky linux advisories RLSA-2025:9079

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-2025-21893 updated cvss 7.1

kernel: keys: Fix UAF in key_put()

  • 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
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-55.17.1.el10_0, perf 6.12.0-55.17.1.el10_0, rtla 6.12.0-55.17.1.el10_0, python3-perf 6.12.0-55.17.1.el10_0, kernel-devel-matched 6.12.0-55.17.1.el10_0, kernel-64k-devel-matched 6.12.0-55.17.1.el10_0, +7 more Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-55.17.1.el10_0, kernel-64k 6.12.0-55.17.1.el10_0, kernel-core 6.12.0-55.17.1.el10_0, kernel-tools 6.12.0-55.17.1.el10_0, kernel-modules 6.12.0-55.17.1.el10_0, kernel-64k-core 6.12.0-55.17.1.el10_0, +27 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-55.17.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.17.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.17.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.17.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.17.1.el10_0 Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-55.17.1.el10_0, kernel-rt-64k 6.12.0-55.17.1.el10_0, kernel-rt-core 6.12.0-55.17.1.el10_0, kernel-rt-modules 6.12.0-55.17.1.el10_0, kernel-rt-64k-core 6.12.0-55.17.1.el10_0, kernel-rt-debug-core 6.12.0-55.17.1.el10_0, +14 more Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-55.17.1.el10_0, kernel-rt-kvm 6.12.0-55.17.1.el10_0, kernel-rt-core 6.12.0-55.17.1.el10_0, kernel-rt-modules 6.12.0-55.17.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.17.1.el10_0, kernel-rt-debug-core 6.12.0-55.17.1.el10_0, +6 more
    fixed: vendor fix RHSA-2025:9079
  • 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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
19 mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

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 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns 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.