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Fencer Vulns
high 7.8

CVE-2025-21919 json

sched/fair: Fix potential memory corruption in child_cfs_rq_on_list

published 2025-04-01 19 mo ago modified 2026-10-15 25 d ago also EUVD-2025-9402

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 14%
public exploits
0
none known

Summary

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

sched/fair: Fix potential memory corruption in child_cfs_rq_on_list

child_cfs_rq_on_list attempts to convert a 'prev' pointer to a cfs_rq. This 'prev' pointer can originate from struct rq's leaf_cfs_rq_list, making the conversion invalid and potentially leading to memory corruption. Depending on the relative positions of leaf_cfs_rq_list and the task group (tg) pointer within the struct, this can cause a memory fault or access garbage data.

The issue arises in list_add_leaf_cfs_rq, where both cfs_rq->leaf_cfs_rq_list and rq->leaf_cfs_rq_list are added to the same leaf list. Also, rq->tmp_alone_branch can be set to rq->leaf_cfs_rq_list.

This adds a check `if (prev == &rq->leaf_cfs_rq_list)` after the main conditional in child_cfs_rq_on_list. This ensures that the container_of operation will convert a correct cfs_rq struct.

This check is sufficient because only cfs_rqs on the same CPU are added to the list, so verifying the 'prev' pointer against the current rq's list head is enough.

Fixes a potential memory corruption issue that due to current struct layout might not be manifesting as a crash but could lead to unpredictable behavior when the layout changes.

Patch / fix

  • Linux Linux 5.15.179, 6.1.131, 6.6.83, 6.12.19, 6.13.7, 6.14
  • linux Debian 12 6.1.133-1
  • linux Debian 14, Debian 13 6.12.19-1

debian advisories DEBIAN-CVE-2025-21919

  • linux Ubuntu 22.04 LTS 5.15.0-140.150
  • linux Ubuntu 24.04 LTS 6.8.0-84.84
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1084.91
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1039.41
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1083.92
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1040.42
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1081.87
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1036.40

ubuntu advisories UBUNTU-CVE-2025-21919

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-rt RHEL 8 4.18.0-553.64.1.rt7.405.el8_10
  • kernel-rt-kvm RHEL 8 4.18.0-553.64.1.rt7.405.el8_10
  • kernel-rt-core RHEL 8 4.18.0-553.64.1.rt7.405.el8_10
  • kernel-rt-modules RHEL 8 4.18.0-553.64.1.rt7.405.el8_10
  • kernel-rt-debug-kvm RHEL 8 4.18.0-553.64.1.rt7.405.el8_10
  • kernel-rt-debug-core RHEL 8 4.18.0-553.64.1.rt7.405.el8_10
  • kernel-rt-debug-modules RHEL 8 4.18.0-553.64.1.rt7.405.el8_10
  • kernel-rt-modules-extra RHEL 8 4.18.0-553.64.1.rt7.405.el8_10

red hat advisories RHSA-2025:14418RHSA-2025:13776RHSA-2025:11851RHSA-2025:11850RHSA-2025:9302RHSA-2025:8374

  • dtb-aarch64 openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-64kb SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-syms SLE Module for Development Tools 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-obs-qa openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-source SLE Module for Development Tools 15 SP6, SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-default SLE Workstation Extension 15 SP6, SLE Module for Legacy 15 SP6, SLE Module for Basesystem 15 SP6 +3 more 6.4.0-150600.23.53.1
  • kernel-kvmsmall openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1

suse advisories SUSE-SU-2025:02000-1SUSE-SU-2025:01972-1SUSE-SU-2025:20413-1SUSE-SU-2025:01967-1SUSE-SU-2025:01965-1SUSE-SU-2025:01964-1

  • kernel AlmaLinux 8 4.18.0-553.64.1.el8_10
  • perf AlmaLinux 8 4.18.0-553.64.1.el8_10
  • bpftool AlmaLinux 8 4.18.0-553.64.1.el8_10
  • kernel-core AlmaLinux 8 4.18.0-553.64.1.el8_10
  • kernel-tools AlmaLinux 8 4.18.0-553.64.1.el8_10
  • python3-perf AlmaLinux 8 4.18.0-553.64.1.el8_10
  • kernel-modules AlmaLinux 8 4.18.0-553.64.1.el8_10
  • kernel-zfcpdump AlmaLinux 8 4.18.0-553.64.1.el8_10

almalinux advisories ALSA-2025:11850ALSA-2025:11851ALSA-2025:9302

  • kernel Rocky Linux 9 5.14.0-570.23.1.el9_6
  • kernel Rocky Linux 10 6.12.0-55.14.1.el10_0
  • kernel-rt Rocky Linux 8 4.18.0-553.64.1.rt7.405.el8_10
  • kernel Rocky Linux 8 4.18.0-553.64.1.el8_10

rocky linux advisories RLSA-2025:9302RLSA-2025:8374RLSA-2025:11851RLSA-2025:11850

  • kernel Azure Linux 3.0 6.6.85.1-2
  • kernel CBL-Mariner 2.0 5.15.180.1-1

azure linux advisories AZL-59919AZL-59966

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-2025-21919 updated cvss 7.0

kernel: sched/fair: Fix potential memory corruption in child_cfs_rq_on_list

  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-570.23.1.el9_6, perf 5.14.0-570.23.1.el9_6, rtla 5.14.0-570.23.1.el9_6, python3-perf 5.14.0-570.23.1.el9_6, kernel-devel-matched 5.14.0-570.23.1.el9_6, kernel-64k-devel-matched 5.14.0-570.23.1.el9_6, +7 more
    fixed: vendor fix RHSA-2025:9302
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-55.14.1.el10_0, perf 6.12.0-55.14.1.el10_0, rtla 6.12.0-55.14.1.el10_0, python3-perf 6.12.0-55.14.1.el10_0, kernel-devel-matched 6.12.0-55.14.1.el10_0, kernel-64k-devel-matched 6.12.0-55.14.1.el10_0, +7 more
    fixed: vendor fix RHSA-2025:8374
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.64.1.el8_10, kernel 4.18.0-553.64.1.el8_10, bpftool 4.18.0-553.64.1.el8_10, kernel-core 4.18.0-553.64.1.el8_10, kernel-tools 4.18.0-553.64.1.el8_10, python3-perf 4.18.0-553.64.1.el8_10, +15 more
    fixed: vendor fix RHSA-2025:11850
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-570.23.1.el9_6, kernel-64k 5.14.0-570.23.1.el9_6, kernel-core 5.14.0-570.23.1.el9_6, kernel-tools 5.14.0-570.23.1.el9_6, kernel-modules 5.14.0-570.23.1.el9_6, kernel-64k-core 5.14.0-570.23.1.el9_6, +27 more
    fixed: vendor fix RHSA-2025:9302
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-55.14.1.el10_0, kernel-64k 6.12.0-55.14.1.el10_0, kernel-core 6.12.0-55.14.1.el10_0, kernel-tools 6.12.0-55.14.1.el10_0, kernel-modules 6.12.0-55.14.1.el10_0, kernel-64k-core 6.12.0-55.14.1.el10_0, +27 more
    fixed: vendor fix RHSA-2025:8374
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) perf 4.18.0-372.157.1.el8_6, kernel 4.18.0-372.157.1.el8_6, bpftool 4.18.0-372.157.1.el8_6, kernel-core 4.18.0-372.157.1.el8_6, kernel-tools 4.18.0-372.157.1.el8_6, python3-perf 4.18.0-372.157.1.el8_6, +8 more Red Hat Enterprise Linux BaseOS E4S (v.8.6) perf 4.18.0-372.157.1.el8_6, kernel 4.18.0-372.157.1.el8_6, bpftool 4.18.0-372.157.1.el8_6, kernel-core 4.18.0-372.157.1.el8_6, kernel-tools 4.18.0-372.157.1.el8_6, python3-perf 4.18.0-372.157.1.el8_6, +15 more
    fixed: vendor fix RHSA-2025:13776
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) perf 4.18.0-477.106.1.el8_8, kernel 4.18.0-477.106.1.el8_8, bpftool 4.18.0-477.106.1.el8_8, kernel-core 4.18.0-477.106.1.el8_8, kernel-tools 4.18.0-477.106.1.el8_8, python3-perf 4.18.0-477.106.1.el8_8, +9 more
    fixed: vendor fix RHSA-2025:14418
  • Red Hat Enterprise Linux BaseOS TUS (v.8.6) perf 4.18.0-372.157.1.el8_6, kernel 4.18.0-372.157.1.el8_6, bpftool 4.18.0-372.157.1.el8_6, kernel-core 4.18.0-372.157.1.el8_6, kernel-tools 4.18.0-372.157.1.el8_6, python3-perf 4.18.0-372.157.1.el8_6, +8 more
    fixed: vendor fix RHSA-2025:13776
show 11 more
  • Red Hat Enterprise Linux BaseOS TUS (v.8.8) perf 4.18.0-477.106.1.el8_8, kernel 4.18.0-477.106.1.el8_8, bpftool 4.18.0-477.106.1.el8_8, kernel-core 4.18.0-477.106.1.el8_8, kernel-tools 4.18.0-477.106.1.el8_8, python3-perf 4.18.0-477.106.1.el8_8, +8 more
    fixed: vendor fix RHSA-2025:14418
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-570.23.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.23.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.23.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.23.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.23.1.el9_6
    fixed: vendor fix RHSA-2025:9302
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-55.14.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.14.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.14.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.14.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.14.1.el10_0
    fixed: vendor fix RHSA-2025:8374
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.64.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.64.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.64.1.el8_10
    fixed: vendor fix RHSA-2025:11850
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-kvm 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-core 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-modules 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-debug-kvm 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-debug-core 4.18.0-553.64.1.rt7.405.el8_10, +4 more
    fixed: vendor fix RHSA-2025:11851
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-570.23.1.el9_6, kernel-rt-64k 5.14.0-570.23.1.el9_6, kernel-rt-core 5.14.0-570.23.1.el9_6, kernel-rt-modules 5.14.0-570.23.1.el9_6, kernel-rt-64k-core 5.14.0-570.23.1.el9_6, kernel-rt-debug-core 5.14.0-570.23.1.el9_6, +14 more
    fixed: vendor fix RHSA-2025:9302
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-55.14.1.el10_0, kernel-rt-64k 6.12.0-55.14.1.el10_0, kernel-rt-core 6.12.0-55.14.1.el10_0, kernel-rt-modules 6.12.0-55.14.1.el10_0, kernel-rt-64k-core 6.12.0-55.14.1.el10_0, kernel-rt-debug-core 6.12.0-55.14.1.el10_0, +14 more
    fixed: vendor fix RHSA-2025:8374
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-570.23.1.el9_6, kernel-rt-kvm 5.14.0-570.23.1.el9_6, kernel-rt-core 5.14.0-570.23.1.el9_6, kernel-rt-modules 5.14.0-570.23.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.23.1.el9_6, kernel-rt-debug-core 5.14.0-570.23.1.el9_6, +6 more
    fixed: vendor fix RHSA-2025:9302
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-55.14.1.el10_0, kernel-rt-kvm 6.12.0-55.14.1.el10_0, kernel-rt-core 6.12.0-55.14.1.el10_0, kernel-rt-modules 6.12.0-55.14.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.14.1.el10_0, kernel-rt-debug-core 6.12.0-55.14.1.el10_0, +6 more
    fixed: vendor fix RHSA-2025:8374
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-core 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-modules 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-debug-core 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-debug-modules 4.18.0-553.64.1.rt7.405.el8_10, kernel-rt-modules-extra 4.18.0-553.64.1.rt7.405.el8_10, +2 more
    fixed: vendor fix RHSA-2025:11851
  • 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
    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 ICSA-26-295-11 updated cvss 7.8

Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.7 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.7
    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 ICSA-26-209-04 updated cvss 7.8

Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.6 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.6 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.6 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.6 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.6
    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
13 mo ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 14% 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 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

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.