Vulnerability Description
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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux Kernel | >= 5.4.288, < 5.4.291 |
Related Weaknesses (CWE)
References
- https://git.kernel.org/stable/c/1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5Patch
- https://git.kernel.org/stable/c/6312555249082d6d8cc5321ff725df05482d8b83Patch
- https://git.kernel.org/stable/c/638ba5089324796c2ee49af10427459c2de35f71Patch
- https://git.kernel.org/stable/c/7b79ca9a1de6a428d486ff52fb3d602321c08f55Patch
- https://git.kernel.org/stable/c/7f31d74fcc556a9166b1bb20515542de7bb939d1Patch
- https://git.kernel.org/stable/c/839ecc583fa00fab785fde1c85a326743657fd32Patch
- https://git.kernel.org/stable/c/98a2c685293aae122f688cde11d9334dddc5d207Patch
- https://git.kernel.org/stable/c/e395fec75ac2dbffc99b4bce57b7f1f3c5449f2cPatch
- https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
FAQ
What is CVE-2025-21703?
CVE-2025-21703 is a vulnerability with a CVSS score of 7.8 (HIGH). 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...
How severe is CVE-2025-21703?
CVE-2025-21703 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-21703?
Check the references section above for vendor advisories and patch information. Affected products include: Linux Linux Kernel.