{"id":"CVE-2025-21703","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetem: Update sch->q.qlen before qdisc_tree_reduce_backlog()\n\nqdisc_tree_reduce_backlog() notifies parent qdisc only if child\nqdisc becomes empty, therefore we need to …","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetem: Update sch->q.qlen before qdisc_tree_reduce_backlog()\n\nqdisc_tree_reduce_backlog() notifies parent qdisc only if child\nqdisc becomes empty, therefore we need to …","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 5.4.288, < 5.4.291","linux_kernel >= 5.10.232, < 5.10.235","linux_kernel >= 5.15.175, < 5.15.179","linux_kernel >= 6.1.121, < 6.1.129","linux_kernel >= 6.6.67, < 6.6.78","linux_kernel >= 6.12.6, < 6.12.14","linux_kernel >= 6.13, < 6.13.3","linux_kernel = 6.14"],"patched":["linux_kernel 6.13.3"],"published":"2025-02-18","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:17:28.087","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-21703","references":[{"url":"https://git.kernel.org/stable/c/1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6312555249082d6d8cc5321ff725df05482d8b83","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/638ba5089324796c2ee49af10427459c2de35f71","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7b79ca9a1de6a428d486ff52fb3d602321c08f55","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7f31d74fcc556a9166b1bb20515542de7bb939d1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/839ecc583fa00fab785fde1c85a326743657fd32","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/98a2c685293aae122f688cde11d9334dddc5d207","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-503939.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00304,"epssPercentile":0.21632,"ingestedAt":"2026-10-15T03:30:12.785Z","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2025-02-18T15:38:37.163490Z"},"slug":"CVE-2025-21703","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetem: Update sch->q.qlen before qdisc_tree_reduce_backlog()\n\nqdisc_tree_reduce_backlog() notifies parent qdisc only if child\nqdisc becomes empty, therefore we need to reduce the backlog of the\nchild qdisc before calling it. Otherwise it would miss the opportunity\nto call cops->qlen_notify(), in the case of DRR, it resulted in UAF\nsince DRR uses ->qlen_notify() to maintain its active list.\n\n## Affected\n\n- `linux_kernel >= 5.4.288, < 5.4.291`\n- `linux_kernel >= 5.10.232, < 5.10.235`\n- `linux_kernel >= 5.15.175, < 5.15.179`\n- `linux_kernel >= 6.1.121, < 6.1.129`\n- `linux_kernel >= 6.6.67, < 6.6.78`\n- `linux_kernel >= 6.12.6, < 6.12.14`\n- `linux_kernel >= 6.13, < 6.13.3`\n- `linux_kernel = 6.14`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.13.3`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}