{"id":"CVE-2025-21703","summary":"netem: Update sch-\u003eq.qlen before qdisc_tree_reduce_backlog()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetem: Update sch-\u003eq.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-\u003eqlen_notify(), in the case of DRR, it resulted in UAF\nsince DRR uses -\u003eqlen_notify() to maintain its active list.","modified":"2026-04-03T13:14:29.071851Z","published":"2025-02-18T14:37:44.261Z","related":["SUSE-SU-2025:01919-1","SUSE-SU-2025:01951-1","SUSE-SU-2025:01967-1","SUSE-SU-2025:02264-1","SUSE-SU-2025:02308-1","SUSE-SU-2025:02320-1","SUSE-SU-2025:02321-1","SUSE-SU-2025:02322-1","SUSE-SU-2025:02537-1","SUSE-SU-2025:1177-1","SUSE-SU-2025:1178-1","SUSE-SU-2025:1180-1","SUSE-SU-2025:1293-1","SUSE-SU-2025:20190-1","SUSE-SU-2025:20192-1","SUSE-SU-2025:20260-1","SUSE-SU-2025:20270-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21703.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6312555249082d6d8cc5321ff725df05482d8b83"},{"type":"WEB","url":"https://git.kernel.org/stable/c/638ba5089324796c2ee49af10427459c2de35f71"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7b79ca9a1de6a428d486ff52fb3d602321c08f55"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7f31d74fcc556a9166b1bb20515542de7bb939d1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/839ecc583fa00fab785fde1c85a326743657fd32"},{"type":"WEB","url":"https://git.kernel.org/stable/c/98a2c685293aae122f688cde11d9334dddc5d207"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21703.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21703"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"83c6ab12f08dcc09d4c5ac86fdb89736b28f1d31"},{"fixed":"e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"216509dda290f6db92c816dd54b83c1df9da9e76"},{"fixed":"7f31d74fcc556a9166b1bb20515542de7bb939d1"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c2047b0e216c8edce227d7c42f99ac2877dad0e4"},{"fixed":"98a2c685293aae122f688cde11d9334dddc5d207"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"10df49cfca73dfbbdb6c4150d859f7e8926ae427"},{"fixed":"7b79ca9a1de6a428d486ff52fb3d602321c08f55"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3824c5fad18eeb7abe0c4fc966f29959552dca3e"},{"fixed":"1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"356078a5c55ec8d2061fcc009fb8599f5b0527f9"},{"fixed":"6312555249082d6d8cc5321ff725df05482d8b83"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"f8d4bc455047cf3903cd6f85f49978987dbb3027"},{"fixed":"839ecc583fa00fab785fde1c85a326743657fd32"},{"fixed":"638ba5089324796c2ee49af10427459c2de35f71"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21703.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}