{"api_version":"1","generated_at":"2026-08-21T20:39:25+00:00","cve":"CVE-2026-74267","urls":{"html":"https://cve.report/CVE-2026-74267","api":"https://cve.report/api/cve/CVE-2026-74267.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74267","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74267"},"summary":{"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":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:22:26","updated_at":"2026-08-17 06:19:20"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/7a05af7f58566682b73578b72ca8e53a268c43bd","name":"https://git.kernel.org/stable/c/7a05af7f58566682b73578b72ca8e53a268c43bd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e8c6dbadf139cb14ea6ed14add6ed6e88504dedd","name":"https://git.kernel.org/stable/c/e8c6dbadf139cb14ea6ed14add6ed6e88504dedd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3","name":"https://git.kernel.org/stable/c/52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/91e0a793a72374c20ab31a40ccec21373e82e973","name":"https://git.kernel.org/stable/c/91e0a793a72374c20ab31a40ccec21373e82e973","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e4615aa6bb7802944ae790cb4b3ef8c1b7491af3","name":"https://git.kernel.org/stable/c/e4615aa6bb7802944ae790cb4b3ef8c1b7491af3","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/eba49fd85995a3851c597fa2d214f8d21736e1d8","name":"https://git.kernel.org/stable/c/eba49fd85995a3851c597fa2d214f8d21736e1d8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/755108bb7a5083e911294c416cfea605dc75632f","name":"https://git.kernel.org/stable/c/755108bb7a5083e911294c416cfea605dc75632f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/bb9cfd874ee884117b33e92a002b9a45b48202f4","name":"https://git.kernel.org/stable/c/bb9cfd874ee884117b33e92a002b9a45b48202f4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74267","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74267","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cc71a757da78dd4aa1b4a9b19cb011833730ccf2 bb9cfd874ee884117b33e92a002b9a45b48202f4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450 7a05af7f58566682b73578b72ca8e53a268c43bd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 829c49b6b2ff45b043739168fd1245e4e1a91a30 eba49fd85995a3851c597fa2d214f8d21736e1d8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f9761a94bae33d26e6a81b31b36e7d776d93dc1 e8c6dbadf139cb14ea6ed14add6ed6e88504dedd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4d55144b12e742404bb3f8fee6038bafbf45619d e4615aa6bb7802944ae790cb4b3ef8c1b7491af3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 342debc12183b51773b3345ba267e9263bdfaaef 755108bb7a5083e911294c416cfea605dc75632f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 342debc12183b51773b3345ba267e9263bdfaaef 91e0a793a72374c20ab31a40ccec21373e82e973 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 342debc12183b51773b3345ba267e9263bdfaaef 52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7a742a9506849d1c1aa71e36c89855ceddc7d58e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e73c838c80dccb9e4f19becc11d9f3cb4a27d483 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.10.241 5.10.261 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.15.190 5.15.212 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.135 6.1.178 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.88 6.6.145 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.24 6.12.97 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.4.297 5.5 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.13.12 6.14 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.14.3 6.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.261 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.212 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.178 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.145 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.97 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.40 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"74267","cve":"CVE-2026-74267","epss":"0.007040000","percentile":"0.502730000","score_date":"2026-08-17","updated_at":"2026-08-18 00:11:46"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/sched/sch_codel.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"bb9cfd874ee884117b33e92a002b9a45b48202f4","status":"affected","version":"cc71a757da78dd4aa1b4a9b19cb011833730ccf2","versionType":"git"},{"lessThan":"7a05af7f58566682b73578b72ca8e53a268c43bd","status":"affected","version":"eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450","versionType":"git"},{"lessThan":"eba49fd85995a3851c597fa2d214f8d21736e1d8","status":"affected","version":"829c49b6b2ff45b043739168fd1245e4e1a91a30","versionType":"git"},{"lessThan":"e8c6dbadf139cb14ea6ed14add6ed6e88504dedd","status":"affected","version":"2f9761a94bae33d26e6a81b31b36e7d776d93dc1","versionType":"git"},{"lessThan":"e4615aa6bb7802944ae790cb4b3ef8c1b7491af3","status":"affected","version":"4d55144b12e742404bb3f8fee6038bafbf45619d","versionType":"git"},{"lessThan":"755108bb7a5083e911294c416cfea605dc75632f","status":"affected","version":"342debc12183b51773b3345ba267e9263bdfaaef","versionType":"git"},{"lessThan":"91e0a793a72374c20ab31a40ccec21373e82e973","status":"affected","version":"342debc12183b51773b3345ba267e9263bdfaaef","versionType":"git"},{"lessThan":"52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3","status":"affected","version":"342debc12183b51773b3345ba267e9263bdfaaef","versionType":"git"},{"status":"affected","version":"7a742a9506849d1c1aa71e36c89855ceddc7d58e","versionType":"git"},{"status":"affected","version":"e73c838c80dccb9e4f19becc11d9f3cb4a27d483","versionType":"git"},{"status":"affected","version":"a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31","versionType":"git"},{"lessThan":"5.10.261","status":"affected","version":"5.10.241","versionType":"semver"},{"lessThan":"5.15.212","status":"affected","version":"5.15.190","versionType":"semver"},{"lessThan":"6.1.178","status":"affected","version":"6.1.135","versionType":"semver"},{"lessThan":"6.6.145","status":"affected","version":"6.6.88","versionType":"semver"},{"lessThan":"6.12.97","status":"affected","version":"6.12.24","versionType":"semver"},{"lessThan":"5.5","status":"affected","version":"5.4.297","versionType":"semver"},{"lessThan":"6.14","status":"affected","version":"6.13.12","versionType":"semver"},{"lessThan":"6.15","status":"affected","version":"6.14.3","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/sched/sch_codel.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.15"},{"lessThan":"6.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.261","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.212","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.178","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.145","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.97","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.40","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.261","versionStartIncluding":"5.10.241","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.212","versionStartIncluding":"5.15.190","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.178","versionStartIncluding":"6.1.135","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.145","versionStartIncluding":"6.6.88","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.97","versionStartIncluding":"6.12.24","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.40","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.5","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4.297","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14.3","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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."}],"metrics":[{"cvssV3_1":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:N - Remote senders reach the bug when packets traverse a QFQ (or other qlen_notify parent) with a codel child: qfq_enqueue() and qfq_dequeue() call the child peek handler during __dev_queue_xmit scheduling, and CoDel can drop there before qlen is restored.\nAC:L - The attacker controls traffic rate, packet size, and CoDel drop behavior to force drops during peek while qlen reads zero; this is a deterministic logic bug, not a race on uncontrollable kernel state or a rare compile-time configuration.\nPR:N - On systems where an operator has already deployed a parent qdisc with a codel child, any remote party that can send packets into the shaped class can trigger the faulty peek/drop path with no account or capabilities on the victim host.\nUI:N - Exploitation requires only attacker-generated traffic (and, for full crash during teardown, attacker-initiated tc reconfiguration); no independent action by another user or administrator is needed at trigger time.\nS:U - The flaw corrupts in-kernel QFQ/CoDel scheduler structures and memory within the same kernel security domain; it does not cross VM, container, or IOMMU authority boundaries.\nC:H - False qlen_notify prematurely deactivates QFQ aggregates while packets remain; the fix commit shows KASAN wild-memory-access on poisoned aggregate list nodes in qfq_deactivate_agg(), giving attacker-influenced reads from freed/corrupted scheduler memory.\nI:H - Corrupted aggregate/class linkage leads to invalid hlist operations and inconsistent scheduler state that can be steered with heap layout control, yielding memory corruption primitives usable for arbitrary kernel writes or control-flow hijack.\nA:H - The published oops is a general protection fault from corrupted QFQ state during qdisc teardown, and the same corruption during live packet scheduling can reliably kernel-panic or hang affected hosts."}]}],"providerMetadata":{"dateUpdated":"2026-08-17T05:45:13.330Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/bb9cfd874ee884117b33e92a002b9a45b48202f4"},{"url":"https://git.kernel.org/stable/c/7a05af7f58566682b73578b72ca8e53a268c43bd"},{"url":"https://git.kernel.org/stable/c/eba49fd85995a3851c597fa2d214f8d21736e1d8"},{"url":"https://git.kernel.org/stable/c/e8c6dbadf139cb14ea6ed14add6ed6e88504dedd"},{"url":"https://git.kernel.org/stable/c/e4615aa6bb7802944ae790cb4b3ef8c1b7491af3"},{"url":"https://git.kernel.org/stable/c/755108bb7a5083e911294c416cfea605dc75632f"},{"url":"https://git.kernel.org/stable/c/91e0a793a72374c20ab31a40ccec21373e82e973"},{"url":"https://git.kernel.org/stable/c/52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3"}],"title":"net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74267","datePublished":"2026-08-15T05:57:42.263Z","dateReserved":"2026-08-15T05:44:03.878Z","dateUpdated":"2026-08-17T05:45:13.330Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:22:26","lastModifiedDate":"2026-08-17 06:19:20","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74267","Ordinal":"1","Title":"net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog duri","CVE":"CVE-2026-74267","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74267","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog duri"}]}}}