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Fencer Vulns
high 7.8

CVE-2025-38000 json

sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()

published 2025-06-06 17 mo ago modified 2026-10-15 24 d ago also EUVD-2025-17141

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 15%
public exploits
0
none known

Summary

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

sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()

When enqueuing the first packet to an HFSC class, hfsc_enqueue() calls the child qdisc's peek() operation before incrementing sch->q.qlen and sch->qstats.backlog. If the child qdisc uses qdisc_peek_dequeued(), this may trigger an immediate dequeue and potential packet drop. In such cases, qdisc_tree_reduce_backlog() is called, but the HFSC qdisc's qlen and backlog have not yet been updated, leading to inconsistent queue accounting. This can leave an empty HFSC class in the active list, causing further consequences like use-after-free.

This patch fixes the bug by moving the increment of sch->q.qlen and sch->qstats.backlog before the call to the child qdisc's peek() operation. This ensures that queue length and backlog are always accurate when packet drops or dequeues are triggered during the peek.

Patch / fix

  • Linux Linux 5.4.294, 5.10.238, 5.15.185, 6.1.141, 6.6.93, 6.12.31, 6.14.9, 6.15
  • linux Debian 12 6.1.147-1
  • linux Debian 14, Debian 13 6.12.32-1

debian advisories DEBIAN-CVE-2025-38000

  • linux Ubuntu 22.04 LTS 5.15.0-143.153
  • linux Ubuntu 24.04 LTS 6.8.0-63.66
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1087.94
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1031.33
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1086.95
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1032.34
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1084.90
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1027.31

ubuntu advisories UBUNTU-CVE-2025-38000

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-2025:20518RHSA-2025:16582RHSA-2025:16583RHSA-2025:16580RHSA-2025:16540RHSA-2025:16541

  • kernel-livepatch-MICRO-6-0-RT_Update_2 Linux Micro 6.1, Linux Micro 6.0 11-1.1
  • kernel-livepatch-MICRO-6-0_Update_2 Linux Micro 6.1, Linux Micro 6.0 11-1.1
  • kernel-livepatch-MICRO-6-0_Update_5 Linux Micro 6.1, Linux Micro 6.0 7-1.2
  • kgraft-patch-SLE12-SP5_Update_61 SLE Live Patching 12 SP5 18-4.1
  • kernel-livepatch-SLE15-SP6_Update_9 SLE Live Patching 15 SP6 6-150600.2.1
  • kernel-livepatch-SLE15-SP6_Update_5 SLE Live Patching 15 SP6 15-150600.2.1
  • kernel-livepatch-SLE15-SP6_Update_3 SLE Live Patching 15 SP6 20-150600.2.1
  • kernel-livepatch-SLE15-SP7_Update_1 SLE Live Patching 15 SP7 3-150700.2.1

suse advisories SUSE-SU-2025:4123-1SUSE-SU-2025:03235-1SUSE-SU-2025:03226-1SUSE-SU-2025:03223-1SUSE-SU-2025:03222-1SUSE-SU-2025:03217-1

  • kernel Azure Linux 3.0 6.6.96.1-1

azure linux advisories AZL-63684

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-2025-38000 updated cvss 7.0

kernel: sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.”
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.”
  • 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 “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:20518
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) perf 5.14.0-70.144.1.el9_0, kernel-devel-matched 5.14.0-70.144.1.el9_0, kernel-debug-devel-matched 5.14.0-70.144.1.el9_0, kernel-debuginfo-common-s390x 5.14.0-70.144.1.el9_0, kernel-zfcpdump-devel-matched 5.14.0-70.144.1.el9_0, kernel-debuginfo-common-x86_64 5.14.0-70.144.1.el9_0, +2 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14744
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) perf 5.14.0-284.128.1.el9_2, rtla 5.14.0-284.128.1.el9_2, kernel-devel-matched 5.14.0-284.128.1.el9_2, kernel-64k-devel-matched 5.14.0-284.128.1.el9_2, kernel-debug-devel-matched 5.14.0-284.128.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.128.1.el9_2, +5 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:12209
  • Red Hat Enterprise Linux BaseOS (v. 8) kpatch-patch-4_18_0-553_30_1 1-9.el8_10, kpatch-patch-4_18_0-553_40_1 1-7.el8_10, kpatch-patch-4_18_0-553_53_1 1-5.el8_10, kpatch-patch-4_18_0-553_72_1 1-2.el8_10, kpatch-patch-4_18_0-553_16_1 1-10.el8_10
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:16582
  • 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, +28 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:20518
  • Red Hat Enterprise Linux BaseOS AUS (v. 8.2) perf 4.18.0-193.165.1.el8_2, kernel 4.18.0-193.165.1.el8_2, bpftool 4.18.0-193.165.1.el8_2, kernel-core 4.18.0-193.165.1.el8_2, kernel-tools 4.18.0-193.165.1.el8_2, python3-perf 4.18.0-193.165.1.el8_2, +8 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14742
show 16 more
  • Red Hat Enterprise Linux BaseOS AUS (v.8.4) perf 4.18.0-305.170.1.el8_4, kernel 4.18.0-305.170.1.el8_4, bpftool 4.18.0-305.170.1.el8_4, kernel-core 4.18.0-305.170.1.el8_4, kernel-tools 4.18.0-305.170.1.el8_4, python3-perf 4.18.0-305.170.1.el8_4, +8 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:15035
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) perf 4.18.0-372.158.1.el8_6, kernel 4.18.0-372.158.1.el8_6, bpftool 4.18.0-372.158.1.el8_6, kernel-core 4.18.0-372.158.1.el8_6, kernel-tools 4.18.0-372.158.1.el8_6, python3-perf 4.18.0-372.158.1.el8_6, +8 more Red Hat Enterprise Linux BaseOS E4S (v.8.6) perf 4.18.0-372.158.1.el8_6, kernel 4.18.0-372.158.1.el8_6, bpftool 4.18.0-372.158.1.el8_6, kernel-core 4.18.0-372.158.1.el8_6, kernel-tools 4.18.0-372.158.1.el8_6, python3-perf 4.18.0-372.158.1.el8_6, +19 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14692
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) perf 4.18.0-477.107.1.el8_8, kernel 4.18.0-477.107.1.el8_8, bpftool 4.18.0-477.107.1.el8_8, kernel-core 4.18.0-477.107.1.el8_8, kernel-tools 4.18.0-477.107.1.el8_8, python3-perf 4.18.0-477.107.1.el8_8, +13 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14511
  • Red Hat Enterprise Linux BaseOS E4S (v.9.0) kernel 5.14.0-70.144.1.el9_0, bpftool 5.14.0-70.144.1.el9_0, kernel-core 5.14.0-70.144.1.el9_0, kernel-tools 5.14.0-70.144.1.el9_0, python3-perf 5.14.0-70.144.1.el9_0, kernel-modules 5.14.0-70.144.1.el9_0, +18 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14744
  • Red Hat Enterprise Linux BaseOS E4S (v.9.2) bpftool 7.0.0-284.128.1.el9_2, kernel 5.14.0-284.128.1.el9_2, kernel-64k 5.14.0-284.128.1.el9_2, kernel-core 5.14.0-284.128.1.el9_2, kernel-tools 5.14.0-284.128.1.el9_2, python3-perf 5.14.0-284.128.1.el9_2, +32 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:12209
  • Red Hat Enterprise Linux BaseOS EUS (v.9.4) kpatch-patch-5_14_0-427_68_2 1-7.el9_4, kpatch-patch-5_14_0-427_84_1 1-2.el9_4, kpatch-patch-5_14_0-427_31_1 1-14.el9_4, kpatch-patch-5_14_0-427_44_1 1-12.el9_4, kpatch-patch-5_14_0-427_55_1 1-10.el9_4
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:16540
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) perf 4.18.0-305.170.1.el8_4, kernel 4.18.0-305.170.1.el8_4, bpftool 4.18.0-305.170.1.el8_4, kernel-core 4.18.0-305.170.1.el8_4, kernel-tools 4.18.0-305.170.1.el8_4, python3-perf 4.18.0-305.170.1.el8_4, +8 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:15035
  • Red Hat Enterprise Linux BaseOS TUS (v.8.6) perf 4.18.0-372.158.1.el8_6, kernel 4.18.0-372.158.1.el8_6, bpftool 4.18.0-372.158.1.el8_6, kernel-core 4.18.0-372.158.1.el8_6, kernel-tools 4.18.0-372.158.1.el8_6, python3-perf 4.18.0-372.158.1.el8_6, +8 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14692
  • Red Hat Enterprise Linux BaseOS TUS (v.8.8) perf 4.18.0-477.107.1.el8_8, kernel 4.18.0-477.107.1.el8_8, bpftool 4.18.0-477.107.1.el8_8, kernel-core 4.18.0-477.107.1.el8_8, kernel-tools 4.18.0-477.107.1.el8_8, python3-perf 4.18.0-477.107.1.el8_8, +8 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14511
  • 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 “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:20518
  • Red Hat Enterprise Linux for Real Time (v. 7 ELS) kernel-rt 3.10.0-1160.137.1.rt56.1289.el7, kernel-rt-trace 3.10.0-1160.137.1.rt56.1289.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.137.1.rt56.1289.el7
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14746
  • 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 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 “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:20518
  • Red Hat Enterprise Linux Server (v. 7 ELS) perf 3.10.0-1160.137.1.el7, kernel 3.10.0-1160.137.1.el7, bpftool 3.10.0-1160.137.1.el7, python-perf 3.10.0-1160.137.1.el7, kernel-kdump 3.10.0-1160.137.1.el7, kernel-tools 3.10.0-1160.137.1.el7, +7 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14748
  • Red Hat Enterprise Linux Server AUS (v. 7.7) perf 3.10.0-1062.99.1.el7, kernel 3.10.0-1062.99.1.el7, bpftool 3.10.0-1062.99.1.el7, python-perf 3.10.0-1062.99.1.el7, kernel-tools 3.10.0-1062.99.1.el7, kernel-tools-libs 3.10.0-1062.99.1.el7, +2 more
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14413
  • Red Hat Enterprise Linux Server Optional (v. 7 ELS) kernel-debuginfo-common-ppc64 3.10.0-1160.137.1.el7, kernel-debuginfo-common-x86_64 3.10.0-1160.137.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-1160.137.1.el7
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14748
  • Red Hat Enterprise Linux Server Optional AUS (v. 7.7) kernel-debuginfo-common-x86_64 3.10.0-1062.99.1.el7
    fixed: vendor fix “To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:14413

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
24 d ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% 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
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

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.