CVE-2025-21703
netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()
CVSS Score
7.8
EPSS Score
0.0%
EPSS Percentile
5th
In the Linux kernel, the following vulnerability has been resolved: netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.
| Vendor | linux |
| Product | linux |
| Ecosystems | |
| Industries | Technology |
| Published | Feb 18, 2025 |
| Last Updated | Apr 2, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
Affected Versions
Linux / Linux
83c6ab12f08dcc09d4c5ac86fdb89736b28f1d31 < e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c 216509dda290f6db92c816dd54b83c1df9da9e76 < 7f31d74fcc556a9166b1bb20515542de7bb939d1 c2047b0e216c8edce227d7c42f99ac2877dad0e4 < 98a2c685293aae122f688cde11d9334dddc5d207 10df49cfca73dfbbdb6c4150d859f7e8926ae427 < 7b79ca9a1de6a428d486ff52fb3d602321c08f55 3824c5fad18eeb7abe0c4fc966f29959552dca3e < 1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5 356078a5c55ec8d2061fcc009fb8599f5b0527f9 < 6312555249082d6d8cc5321ff725df05482d8b83 f8d4bc455047cf3903cd6f85f49978987dbb3027 < 839ecc583fa00fab785fde1c85a326743657fd32 f8d4bc455047cf3903cd6f85f49978987dbb3027 < 638ba5089324796c2ee49af10427459c2de35f71
Linux / Linux
6.13
References
git.kernel.org: https://git.kernel.org/stable/c/e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c git.kernel.org: https://git.kernel.org/stable/c/7f31d74fcc556a9166b1bb20515542de7bb939d1 git.kernel.org: https://git.kernel.org/stable/c/98a2c685293aae122f688cde11d9334dddc5d207 git.kernel.org: https://git.kernel.org/stable/c/7b79ca9a1de6a428d486ff52fb3d602321c08f55 git.kernel.org: https://git.kernel.org/stable/c/1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5 git.kernel.org: https://git.kernel.org/stable/c/6312555249082d6d8cc5321ff725df05482d8b83 git.kernel.org: https://git.kernel.org/stable/c/839ecc583fa00fab785fde1c85a326743657fd32 git.kernel.org: https://git.kernel.org/stable/c/638ba5089324796c2ee49af10427459c2de35f71 lists.debian.org: https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html