{"id":"CVE-2026-74267","revision":"4a3cbb8778024f95a954c54e53abf564","records":[{"revision":"4a3cbb8778024f95a954c54e53abf564","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-74267","aliases":[],"title":"net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen\n\nWhenever codel drops packets during peek, it calls\nqdisc_tree_reduce_backlog. An issue arises because it calls\nqdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops\nto zero, but peek returns an skb, the parent's qlen_notify callback will\nbe executed even though codel still has 1 packet on the queue and, thus,\nwill mistakenly deactivate the parent's class causing issues like a wild\nmemory access when qfq has codel as a child:\n\n[ 36.339843][ T370] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI\n[ 36.340408][ T370] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]\n[ 36.340737][ T370] CPU: 2 UID: 0 PID: 370 Comm: tc Not tainted 7.1.0-rc5-00287-g66e13b626592 #87 PREEMPT(full)\n[ 36.341113][ T370] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[ 36.341357][ T370] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:1029 (discriminator 2) include/linux/list.h:1043 (discriminator 2) net/sched/sch_qfq.c:1369 (discriminator 2) net/sched/sch_qfq.c:1395 (discriminator 2)) sch_qfq\n[ 36.342221][ T370] RSP: 0018:ffff8881100ef370 EFLAGS: 00010216\n[ 36.342422][ T370] RAX: 0000000000000000 RBX: ffff8881058a9568 RCX: dffffc0000000000\n[ 36.342664][ T370] RDX: 1ffff11021064dc3 RSI: ffff888108326e00 RDI: dffffc0000000000\n[ 36.342905][ T370] RBP: ffff8881058a8280 R08: dead000000000122 R09: 1bd5a00000000024\n[ 36.343140][ T370] R10: fffffbfff2940329 R11: fffffbfff2940329 R12: 0000000000000000\n[ 36.343383][ T370] R13: dead000000000100 R14: ffff8881058a9580 R15: ffff8881058a9578\n[ 36.343631][ T370] FS: 00007fc04b0ca780(0000) GS:ffff888184fef000(0000) knlGS:0000000000000000\n[ 36.343911][ T370] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 36.344116][ T370] CR2: 0000557c02c02000 CR3: 000000010e0ba000 CR4: 0000000000750ef0\n[ 36.344359][ T370] PKRU: 55555554\n[ 36.344481][ T370] Call Trace:\n...\n[ 36.345054][ T370] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq\n[ 36.345222][ T370] qdisc_reset (net/sched/sch_generic.c:1057)\n[ 36.345503][ T370] __qdisc_destroy (net/sched/sch_generic.c:1096)\n[ 36.345677][ T370] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159)\n[ 36.346335][ T370] tc_get_qdisc (net/sched/sch_api.c:1528 net/sched/sch_api.c:1556)\n\nFix this by only calling qdisc_tree_reduce_backlog in peek after the\nqlen is restored.","state":0,"publishedAt":"2026-08-15T05:57:42.263+00:00","modifiedAt":"2026-10-16T18:55:28.845+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/sched/sch_codel.c\"\n ],\n \"versions\": [\n {\n \"version\": \"cc71a757da78dd4aa1b4a9b19cb011833730ccf2\",\n \"lessThan\": \"bb9cfd874ee884117b33e92a002b9a45b48202f4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450\",\n \"lessThan\": \"7a05af7f58566682b73578b72ca8e53a268c43bd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"829c49b6b2ff45b043739168fd1245e4e1a91a30\",\n \"lessThan\": \"eba49fd85995a3851c597fa2d214f8d21736e1d8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2f9761a94bae33d26e6a81b31b36e7d776d93dc1\",\n \"lessThan\": \"e8c6dbadf139cb14ea6ed14add6ed6e88504dedd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"4d55144b12e742404bb3f8fee6038bafbf45619d\",\n \"lessThan\": \"e4615aa6bb7802944ae790cb4b3ef8c1b7491af3\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"342debc12183b51773b3345ba267e9263bdfaaef\",\n \"lessThan\": \"755108bb7a5083e911294c416cfea605dc75632f\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"342debc12183b51773b3345ba267e9263bdfaaef\",\n \"lessThan\": \"91e0a793a72374c20ab31a40ccec21373e82e973\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"342debc12183b51773b3345ba267e9263bdfaaef\",\n \"lessThan\": \"52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"7a742a9506849d1c1aa71e36c89855ceddc7d58e\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e73c838c80dccb9e4f19becc11d9f3cb4a27d483\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"5.10.241\",\n \"lessThan\": \"5.10.261\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.190\",\n \"lessThan\": \"5.15.212\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.135\",\n \"lessThan\": \"6.1.178\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.88\",\n \"lessThan\": \"6.6.145\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.24\",\n \"lessThan\": \"6.12.97\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.4.297\",\n \"lessThan\": \"5.5\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.13.12\",\n \"lessThan\": \"6.14\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.14.3\",\n \"lessThan\": \"6.15\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/sched/sch_codel.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6.15\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.15\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.261\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.212\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.178\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.145\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.97\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.40\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.5\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/bb9cfd874ee884117b33e92a002b9a45b48202f4","https://git.kernel.org/stable/c/7a05af7f58566682b73578b72ca8e53a268c43bd","https://git.kernel.org/stable/c/eba49fd85995a3851c597fa2d214f8d21736e1d8","https://git.kernel.org/stable/c/e8c6dbadf139cb14ea6ed14add6ed6e88504dedd","https://git.kernel.org/stable/c/e4615aa6bb7802944ae790cb4b3ef8c1b7491af3","https://git.kernel.org/stable/c/755108bb7a5083e911294c416cfea605dc75632f","https://git.kernel.org/stable/c/91e0a793a72374c20ab31a40ccec21373e82e973","https://git.kernel.org/stable/c/52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74267","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-74267","identifiers":["CVE-2026-74267"]},"retained":false,"historicalAffected":[]}],"coverage":[]}