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Fencer Vulns
high 7.8

CVE-2025-21791 json

vrf: use RCU protection in l3mdev_l3_out()

published 2025-02-27 20 mo ago modified 2026-10-15 25 d ago also EUVD-2025-5134

cvss
7.8
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 19%
public exploits
0
none known

Summary

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

vrf: use RCU protection in l3mdev_l3_out()

l3mdev_l3_out() can be called without RCU being held:

raw_sendmsg() ip_push_pending_frames() ip_send_skb() ip_local_out() __ip_local_out() l3mdev_ip_out()

Add rcu_read_lock() / rcu_read_unlock() pair to avoid a potential UAF.

Patch / fix

  • Linux Linux 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4, 6.14
  • linux Debian 12 6.1.129-1
  • linux Debian 14, Debian 13 6.12.16-1

debian advisories DEBIAN-CVE-2025-21791

  • linux Ubuntu 20.04 LTS 5.4.0-216.236
  • linux Ubuntu 22.04 LTS 5.15.0-140.150
  • linux Ubuntu 24.04 LTS 6.8.0-78.78
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1146.156
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1084.91
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1035.37
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1149.158
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1083.92

ubuntu advisories UBUNTU-CVE-2025-21791

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 5.14.0-611.5.1.el9_7
  • rv RHEL 9 5.14.0-611.5.1.el9_7
  • perf RHEL 9 5.14.0-611.5.1.el9_7
  • rtla RHEL 9 5.14.0-611.5.1.el9_7
  • libperf RHEL 9 5.14.0-611.5.1.el9_7
  • kernel-rt RHEL 9 5.14.0-611.5.1.el9_7
  • kernel-64k RHEL 9 5.14.0-611.5.1.el9_7
  • kernel-core RHEL 9 5.14.0-611.5.1.el9_7

red hat advisories RHSA-2026:2352RHSA-2025:20518RHSA-2025:20095

  • kernel-livepatch-MICRO-6-0-RT_Update_3 Linux Micro 6.0 13-1.2
  • kernel-livepatch-MICRO-6-0-RT_Update_2 Linux Micro 6.1, Linux Micro 6.0 13-1.1
  • kernel-livepatch-MICRO-6-0-RT_Update_4 Linux Micro 6.1, Linux Micro 6.0 10-1.1
  • kernel-livepatch-MICRO-6-0-RT_Update_5 Linux Micro 6.1, Linux Micro 6.0 9-1.1
  • kernel-livepatch-MICRO-6-0_Update_2 Linux Micro 6.1, Linux Micro 6.0 13-1.1
  • kernel-livepatch-MICRO-6-0_Update_4 Linux Micro 6.1, Linux Micro 6.0 11-1.2
  • kernel-livepatch-MICRO-6-0_Update_5 Linux Micro 6.1, Linux Micro 6.0 9-1.2
  • kernel-livepatch-MICRO-6-0_Update_3 Linux Micro 6.0 13-1.2

suse advisories SUSE-SU-2025:4123-1SUSE-SU-2025:03578-1SUSE-SU-2025:03580-1SUSE-SU-2025:03577-1SUSE-SU-2025:03571-1SUSE-SU-2025:03569-1

  • kernel AlmaLinux 10 6.12.0-124.8.1.el10_1
  • rv AlmaLinux 10 6.12.0-124.8.1.el10_1
  • perf AlmaLinux 10 6.12.0-124.8.1.el10_1
  • rtla AlmaLinux 10 6.12.0-124.8.1.el10_1
  • libperf AlmaLinux 10 6.12.0-124.8.1.el10_1
  • kernel-rt AlmaLinux 10 6.12.0-124.8.1.el10_1
  • kernel-64k AlmaLinux 10 6.12.0-124.8.1.el10_1
  • kernel-core AlmaLinux 10 6.12.0-124.8.1.el10_1

almalinux advisories ALSA-2025:20095ALSA-2025:20518

  • kernel Rocky Linux 10 6.12.0-124.8.1.el10_1
  • kernel Rocky Linux 9 5.14.0-611.5.1.el9_7

rocky linux advisories RLSA-2025:20095RLSA-2025:20518

  • kernel CBL-Mariner 2.0 5.15.179.1-1
  • kernel Azure Linux 3.0 6.6.82.1-1

azure linux advisories AZL-58476AZL-58566

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2025-21791 updated cvss 7.1

kernel: vrf: use RCU protection in l3mdev_l3_out()

  • 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
    affected: workaround, no fix planned “Out of support scope”
  • 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 CodeReady Linux Builder EUS (v.9.6) libperf 5.14.0-570.86.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.86.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.86.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.86.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.86.1.el9_6
    fixed: vendor fix RHSA-2026:2352
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-611.5.1.el9_7, perf 5.14.0-611.5.1.el9_7, rtla 5.14.0-611.5.1.el9_7, python3-perf 5.14.0-611.5.1.el9_7, kernel-devel-matched 5.14.0-611.5.1.el9_7, kernel-64k-devel-matched 5.14.0-611.5.1.el9_7, +7 more
    fixed: vendor fix RHSA-2025:20518
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-124.8.1.el10_1, perf 6.12.0-124.8.1.el10_1, rtla 6.12.0-124.8.1.el10_1, python3-perf 6.12.0-124.8.1.el10_1, kernel-devel-matched 6.12.0-124.8.1.el10_1, kernel-64k-devel-matched 6.12.0-124.8.1.el10_1, +7 more
    fixed: vendor fix RHSA-2025:20095
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) rv 5.14.0-570.86.1.el9_6, perf 5.14.0-570.86.1.el9_6, rtla 5.14.0-570.86.1.el9_6, python3-perf 5.14.0-570.86.1.el9_6, kernel-devel-matched 5.14.0-570.86.1.el9_6, kernel-64k-devel-matched 5.14.0-570.86.1.el9_6, +7 more
    fixed: vendor fix RHSA-2026:2352
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-611.5.1.el9_7, kernel-64k 5.14.0-611.5.1.el9_7, kernel-core 5.14.0-611.5.1.el9_7, kernel-tools 5.14.0-611.5.1.el9_7, kernel-modules 5.14.0-611.5.1.el9_7, kernel-64k-core 5.14.0-611.5.1.el9_7, +27 more
    fixed: vendor fix RHSA-2025:20518
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-124.8.1.el10_1, kernel-64k 6.12.0-124.8.1.el10_1, kernel-core 6.12.0-124.8.1.el10_1, kernel-tools 6.12.0-124.8.1.el10_1, kernel-modules 6.12.0-124.8.1.el10_1, kernel-64k-core 6.12.0-124.8.1.el10_1, +28 more
    fixed: vendor fix RHSA-2025:20095
show 9 more
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel 5.14.0-570.86.1.el9_6, kernel-64k 5.14.0-570.86.1.el9_6, kernel-core 5.14.0-570.86.1.el9_6, kernel-tools 5.14.0-570.86.1.el9_6, kernel-modules 5.14.0-570.86.1.el9_6, kernel-64k-core 5.14.0-570.86.1.el9_6, +27 more
    fixed: vendor fix RHSA-2026:2352
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-611.5.1.el9_7, kernel-debuginfo-common-s390x 5.14.0-611.5.1.el9_7, kernel-debuginfo-common-x86_64 5.14.0-611.5.1.el9_7, kernel-debuginfo-common-aarch64 5.14.0-611.5.1.el9_7, kernel-debuginfo-common-ppc64le 5.14.0-611.5.1.el9_7
    fixed: vendor fix RHSA-2025:20518
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-124.8.1.el10_1, kernel-debuginfo-common-s390x 6.12.0-124.8.1.el10_1, kernel-debuginfo-common-x86_64 6.12.0-124.8.1.el10_1, kernel-debuginfo-common-aarch64 6.12.0-124.8.1.el10_1, kernel-debuginfo-common-ppc64le 6.12.0-124.8.1.el10_1
    fixed: vendor fix RHSA-2025:20095
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-611.5.1.el9_7, kernel-rt-64k 5.14.0-611.5.1.el9_7, kernel-rt-core 5.14.0-611.5.1.el9_7, kernel-rt-modules 5.14.0-611.5.1.el9_7, kernel-rt-64k-core 5.14.0-611.5.1.el9_7, kernel-rt-debug-core 5.14.0-611.5.1.el9_7, +14 more
    fixed: vendor fix RHSA-2025:20518
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-124.8.1.el10_1, kernel-rt-64k 6.12.0-124.8.1.el10_1, kernel-rt-core 6.12.0-124.8.1.el10_1, kernel-rt-modules 6.12.0-124.8.1.el10_1, kernel-rt-64k-core 6.12.0-124.8.1.el10_1, kernel-rt-debug-core 6.12.0-124.8.1.el10_1, +14 more
    fixed: vendor fix RHSA-2025:20095
  • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt 5.14.0-570.86.1.el9_6, kernel-rt-64k 5.14.0-570.86.1.el9_6, kernel-rt-core 5.14.0-570.86.1.el9_6, kernel-rt-modules 5.14.0-570.86.1.el9_6, kernel-rt-64k-core 5.14.0-570.86.1.el9_6, kernel-rt-debug-core 5.14.0-570.86.1.el9_6, +14 more
    fixed: vendor fix RHSA-2026:2352
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-611.5.1.el9_7, kernel-rt-core 5.14.0-611.5.1.el9_7, kernel-rt-modules 5.14.0-611.5.1.el9_7, kernel-rt-debug-core 5.14.0-611.5.1.el9_7, kernel-rt-modules-core 5.14.0-611.5.1.el9_7, kernel-rt-debug-modules 5.14.0-611.5.1.el9_7, +4 more
    fixed: vendor fix RHSA-2025:20518
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-124.8.1.el10_1, kernel-rt-core 6.12.0-124.8.1.el10_1, kernel-rt-modules 6.12.0-124.8.1.el10_1, kernel-rt-debug-core 6.12.0-124.8.1.el10_1, kernel-rt-modules-core 6.12.0-124.8.1.el10_1, kernel-rt-debug-modules 6.12.0-124.8.1.el10_1, +4 more
    fixed: vendor fix RHSA-2025:20095
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt 5.14.0-570.86.1.el9_6, kernel-rt-kvm 5.14.0-570.86.1.el9_6, kernel-rt-core 5.14.0-570.86.1.el9_6, kernel-rt-modules 5.14.0-570.86.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.86.1.el9_6, kernel-rt-debug-core 5.14.0-570.86.1.el9_6, +6 more
    fixed: vendor fix RHSA-2026:2352

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 ICSA-26-295-16 updated cvss 7.8

Siemens SIMATIC S7-1500 TM MFP

  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
20 mo ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 19% 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
NVD 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
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

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.