CVE-2025-21971net_sched: Prevent creation of classes with TC_H_ROOT
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 15, 2026
Affected products
Linux Linux linux:linux (from the name) | from 066a3b5b2346febf9a655b444567b7138e3bb939 before e05d9938b1b0ac40b6054cc5fa0ccbd9afd5ed4c; 066a3b5b2346febf9a655b444567b7138e3bb939 builds before 7a82fe67a9f4d7123d8e5ba8f0f0806c28695006; 066a3b5b2346febf9a655b444567b7138e3bb939 builds before 003d92c91cdb5a64b25a9a74cb8543aac9a8bb48; from 066a3b5b2346febf9a655b444567b7138e3bb939 before e5ee00607bbfc97ef1526ea95b6b2458ac9e7cb7; from 066a3b5b2346febf9a655b444567b7138e3bb939 before 78533c4a29ac3aeddce4b481770beaaa4f3bfb67; 066a3b5b2346febf9a655b444567b7138e3bb939 builds before 5c3ca9cb48b51bd72bf76b8b05e24f3cd53db5e7; from 066a3b5b2346febf9a655b444567b7138e3bb939 before 94edfdfb9505ab608e86599d1d1e38c83816fc1c; 066a3b5b2346febf9a655b444567b7138e3bb939 builds before 0c3057a5a04d07120b3d0ec9c79568fceb9c921e | CNA record |
linux linux_kernel linux:linux_kernel | from 2.6.26 before 5.4.292; from 5.5 before 5.10.236; from 5.11 before 5.15.180; from 5.16 before 6.1.132; from 6.2 before 6.6.84; from 6.7 before 6.12.20; from 6.13 before 6.13.8; 2.6.25; and 6 more ranges | NVD |
References
- https://git.kernel.org/stable/c/e05d9938b1b0ac40b6054cc5fa0ccbd9afd5ed4cpatch
- https://git.kernel.org/stable/c/7a82fe67a9f4d7123d8e5ba8f0f0806c28695006patch
- https://git.kernel.org/stable/c/003d92c91cdb5a64b25a9a74cb8543aac9a8bb48patch
- https://git.kernel.org/stable/c/e5ee00607bbfc97ef1526ea95b6b2458ac9e7cb7patch
- https://git.kernel.org/stable/c/78533c4a29ac3aeddce4b481770beaaa4f3bfb67patch
- https://git.kernel.org/stable/c/5c3ca9cb48b51bd72bf76b8b05e24f3cd53db5e7patch
- https://git.kernel.org/stable/c/94edfdfb9505ab608e86599d1d1e38c83816fc1cpatch
- https://git.kernel.org/stable/c/0c3057a5a04d07120b3d0ec9c79568fceb9c921epatch
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.