CVE-2025-21971

Aliases:UBUNTU-CVE-2025-21971DEBIAN-CVE-2025-21971
Advisory lineage Upstream: 0 Downstream: 120
Modified
Published: 01 Apr 2025, 15:47
Last modified:05 Aug 2026, 11:55

Vulnerability Summary

Overall Risk (default)
medium
31/100
CVSS Score
7.8 HIGH
v3.1 (cve.org)
EPSS Score
0.22% LOW
0% probability +0.13%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

01 Apr 2025, 15:47
Published
Vulnerability first disclosed
05 Aug 2026, 11:55
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: net_sched: Prevent creation of classes with TC_H_ROOT The function qdisc_tree_reduce_backlog() uses TC_H_ROOT as a termination condition when traversing up the qdisc tree to update parent backlog counters. However, if a class is created with classid TC_H_ROOT, the traversal terminates prematurely at this class instead of reaching the actual root qdisc, causing parent statistics to be incorrectly maintained. In case of DRR, this could lead to a crash as reported by Mingi Cho. Prevent the creation of any Qdisc class with classid TC_H_ROOT (0xFFFFFFFF) across all qdisc types, as suggested by Jamal.

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  • v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.22%• Percentile: 13%

Techniques & Countermeasures

  • CWE-835•Loop with Unreachable Exit Condition ('Infinite Loop')

    The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

Affected Systems

  • debian•linux

    < 5.10.237-1 | < 6.1.133-1 | < 6.12.20-1 | < 6.12.20-1

  • debian•linux-6.1

    < 6.1.137-1~deb11u1

  • ubuntu•linux

    all | < 4.4.0-268.302 | < 4.15.0-237.249 | < 5.4.0-216.236 | < 5.15.0-140.150 | < 6.8.0-60.63

  • ubuntu•linux-allwinner-5.19

    all

  • ubuntu•linux-aws

    < 4.4.0-1143.149 | < 4.4.0-1181.196 | < 4.15.0-1180.193 | < 5.4.0-1146.156 | < 5.15.0-1084.91 | < 6.8.0-1029.31

  • ubuntu•linux-aws-5.0

    all

  • ubuntu•linux-aws-5.11

    all

  • ubuntu•linux-aws-5.13

    all

  • ubuntu•linux-aws-5.15

    < 5.15.0-1084.91~20.04.1

  • ubuntu•linux-aws-5.19

    all

  • ubuntu•linux-aws-5.3

    all

  • ubuntu•linux-aws-5.4

    < 5.4.0-1146.156~18.04.1

  • ubuntu•linux-aws-5.8

    all

  • ubuntu•linux-aws-6.2

    all

  • ubuntu•linux-aws-6.5

    all

  • ubuntu•linux-aws-6.8

    < 6.8.0-1029.31~22.04.1

  • ubuntu•linux-aws-fips

    < 4.15.0-2118.124 | all | < 5.4.0-1146.156+fips1 | < 5.15.0-1084.91+fips1

  • ubuntu•linux-aws-hwe

    < 4.15.0-1180.193~16.04.1

  • ubuntu•linux-azure

    < 4.15.0-1188.203~14.04.1 | < 4.15.0-1188.203~16.04.1 | all | < 5.4.0-1151.158 | < 5.15.0-1089.98 | < 6.8.0-1029.34

  • ubuntu•linux-azure-4.15

    < 4.15.0-1188.203

  • ubuntu•linux-azure-5.11

    all

  • ubuntu•linux-azure-5.13

    all

  • ubuntu•linux-azure-5.15

    < 5.15.0-1089.98~20.04.1

  • ubuntu•linux-azure-5.19

    all

  • ubuntu•linux-azure-5.3

    all

  • ubuntu•linux-azure-5.4

    < 5.4.0-1151.158~18.04.1

  • ubuntu•linux-azure-5.8

    all

  • ubuntu•linux-azure-6.11

    < 6.11.0-1015.15~24.04.1

  • ubuntu•linux-azure-6.2

    all

  • ubuntu•linux-azure-6.5

    all

  • ubuntu•linux-azure-6.8

    < 6.8.0-1029.34~22.04.1

  • ubuntu•linux-azure-edge

    all

  • ubuntu•linux-azure-fde

    all | all

  • ubuntu•linux-azure-fde-5.19

    all

  • ubuntu•linux-azure-fde-6.2

    all

  • ubuntu•linux-azure-fips

    < 4.15.0-2097.103 | all | < 5.4.0-1151.158+fips1 | < 5.15.0-1089.98+fips1

  • ubuntu•linux-azure-nvidia

    < 6.8.0-1016.17

  • ubuntu•linux-bluefield

    all | < 5.4.0-1105.112 | < 5.15.0-1066.68

  • ubuntu•linux-fips

    < 4.4.0-1113.120 | all | < 4.15.0-1135.146 | < 5.4.0-1120.130 | < 5.15.0-140.150+fips1 | < 6.8.0-78.78+fips1

  • ubuntu•linux-gcp

    < 4.15.0-1173.190~16.04.1 | all | < 5.4.0-1149.158 | < 5.15.0-1083.92 | < 6.8.0-1030.32

  • ubuntu•linux-gcp-4.15

    < 4.15.0-1173.190

  • ubuntu•linux-gcp-5.11

    all

  • ubuntu•linux-gcp-5.13

    all

  • ubuntu•linux-gcp-5.15

    < 5.15.0-1083.92~20.04.1

  • ubuntu•linux-gcp-5.19

    all

  • ubuntu•linux-gcp-5.3

    all

  • ubuntu•linux-gcp-5.4

    < 5.4.0-1149.158~18.04.1

  • ubuntu•linux-gcp-5.8

    all

  • ubuntu•linux-gcp-6.11

    < 6.11.0-1015.15~24.04.1

  • ubuntu•linux-gcp-6.2

    all

Showing first 50 affected entries in server-rendered view.

References (66)