CVE-2025-21971

Advisory lineage Upstream: 0 Downstream: 120
Modified
Published: 01 Apr 2025, 15:47
Last modified:11 May 2026, 21:10

Vulnerability Summary

Overall Risk (default)
low
22/100
CVSS Score
5.5 MEDIUM
v3.1 (nvd)
EPSS Score
0.02% LOW
0% probability -0.07%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

01 Apr 2025, 15:47
Published
Vulnerability first disclosed
11 May 2026, 21:10
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

EPSS Trends

Current EPSS score: 0.02%• Percentile: 5%

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

  • linux•linux

    ≥ 066a3b5b2346febf9a655b444567b7138e3bb939, < e05d9938b1b0ac40b6054cc5fa0ccbd9afd5ed4c | ≥ 066a3b5b2346febf9a655b444567b7138e3bb939, < 7a82fe67a9f4d7123d8e5ba8f0f0806c28695006 | ≥ 066a3b5b2346febf9a655b444567b7138e3bb939, < 003d92c91cdb5a64b25a9a74cb8543aac9a8bb48 | ≥ 066a3b5b2346febf9a655b444567b7138e3bb939, < e5ee00607bbfc97ef1526ea95b6b2458ac9e7cb7 | ≥ 066a3b5b2346febf9a655b444567b7138e3bb939, < 78533c4a29ac3aeddce4b481770beaaa4f3bfb67 | ≥ 066a3b5b2346febf9a655b444567b7138e3bb939, < 5c3ca9cb48b51bd72bf76b8b05e24f3cd53db5e7 | ≥ 066a3b5b2346febf9a655b444567b7138e3bb939, < 94edfdfb9505ab608e86599d1d1e38c83816fc1c | ≥ 066a3b5b2346febf9a655b444567b7138e3bb939, < 0c3057a5a04d07120b3d0ec9c79568fceb9c921e | 2.6.25

  • linux•linux_kernel

    ≥ 2.6.26, < 5.4.292 | ≥ 5.5, < 5.10.236 | ≥ 5.11, < 5.15.180 | ≥ 5.16, < 6.1.132 | ≥ 6.2, < 6.6.84 | ≥ 6.7, < 6.12.20 | ≥ 6.13, < 6.13.8 | 2.6.25 | 6.14:rc1 | 6.14:rc2 | 6.14:rc3 | 6.14:rc4 | 6.14:rc5 | 6.14:rc6

References (10)