CVE-2025-21971
Estado: ModificadaMedia (5.5)—
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
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.22%
- Percentil entre todas las CVEs puntuadas: 12
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- CWE-835
Referencias
- https://git.kernel.org/stable/c/003d92c91cdb5a64b25a9a74cb8543aac9a8bb48
- https://git.kernel.org/stable/c/0c3057a5a04d07120b3d0ec9c79568fceb9c921e
- https://git.kernel.org/stable/c/5c3ca9cb48b51bd72bf76b8b05e24f3cd53db5e7
- https://git.kernel.org/stable/c/78533c4a29ac3aeddce4b481770beaaa4f3bfb67
- https://git.kernel.org/stable/c/7a82fe67a9f4d7123d8e5ba8f0f0806c28695006
- https://git.kernel.org/stable/c/94edfdfb9505ab608e86599d1d1e38c83816fc1c
- https://git.kernel.org/stable/c/e05d9938b1b0ac40b6054cc5fa0ccbd9afd5ed4c
- https://git.kernel.org/stable/c/e5ee00607bbfc97ef1526ea95b6b2458ac9e7cb7
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: Prevent creation of classes with TC_H_ROOT\n\nThe function qdisc_tree_reduce_backlog() uses TC_H_ROOT as a termination\ncondition when traversing up the qdisc tree to update parent backlog\ncounters. However, if a class is created with classid TC_H_ROOT, the\ntraversal terminates prematurely at this class instead of reaching the\nactual root qdisc, causing parent statistics to be incorrectly maintained.\nIn case of DRR, this could lead to a crash as reported by Mingi Cho.\n\nPrevent the creation of any Qdisc class with classid TC_H_ROOT\n(0xFFFFFFFF) across all qdisc types, as suggested by Jamal."
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"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net_sched: Impide la creación de clases con TC_H_ROOT La función qdisc_tree_reduce_backlog() usa TC_H_ROOT como condición de terminación al recorrer el árbol qdisc para actualizar los contadores de backlog primarios. Sin embargo, si se crea una clase con classid TC_H_ROOT, el recorrido termina prematuramente en esta clase en lugar de alcanzar la qdisc root real, lo que provoca que las estadísticas primarias se mantengan incorrectamente. En caso de DRR, esto podría provocar un fallo como lo informó Mingi Cho. Impide la creación de cualquier clase Qdisc con classid TC_H_ROOT (0xFFFFFFFF) en todos los tipos de qdisc, como sugirió Jamal."
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