{"id":"CVE-2026-80630","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen\n\nWhenever fq_codel drops packets during peek, it calls\nqdisc_tree_reduc…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen\n\nWhenever fq_codel drops packets during peek, it calls\nqdisc_tree_reduc…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-664"],"vendor":"Linux","product":"Linux","affected":["Linux >= cc71a757da78dd4aa1b4a9b19cb011833730ccf2 < 3e515188393e62a718ccebee651ee74514104ff6","Linux >= eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450 < 20dd591d8f951e1e6aca5052be8785e6181055e2","Linux >= 829c49b6b2ff45b043739168fd1245e4e1a91a30 < 94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80","Linux >= 2f9761a94bae33d26e6a81b31b36e7d776d93dc1 < acc08a0c7f37ebb1901144e03a7cba7d4afd9203","Linux >= 4d55144b12e742404bb3f8fee6038bafbf45619d < 7c09843fd2b44d9bf0de798683861d1aecd62a08","Linux >= 342debc12183b51773b3345ba267e9263bdfaaef < 0500af8630c3253f0dde879bd3a73a06bb2f2b3f","Linux >= 342debc12183b51773b3345ba267e9263bdfaaef < af54df2f44d9605614bc7ed96640302a240a9a62","Linux >= 342debc12183b51773b3345ba267e9263bdfaaef < 097f6fc7b1ae362dd7a9444b2572162fda73b284","Linux 7a742a9506849d1c1aa71e36c89855ceddc7d58e","Linux e73c838c80dccb9e4f19becc11d9f3cb4a27d483","Linux a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31","Linux >= 5.10.241 < 5.10.261","Linux >= 5.15.190 < 5.15.212","Linux >= 6.1.135 < 6.1.178","Linux >= 6.6.88 < 6.6.145","Linux >= 6.12.24 < 6.12.97","Linux >= 5.4.297 < 5.5","Linux >= 6.13.12 < 6.14","Linux >= 6.14.3 < 6.15","Linux 6.15"],"published":"2026-08-28","updated":"2026-10-16","sourceUpdated":"2026-10-16T20:18:04.520","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-80630","references":[{"url":"https://git.kernel.org/stable/c/0500af8630c3253f0dde879bd3a73a06bb2f2b3f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/097f6fc7b1ae362dd7a9444b2572162fda73b284","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/20dd591d8f951e1e6aca5052be8785e6181055e2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3e515188393e62a718ccebee651ee74514104ff6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7c09843fd2b44d9bf0de798683861d1aecd62a08","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/acc08a0c7f37ebb1901144e03a7cba7d4afd9203","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/af54df2f44d9605614bc7ed96640302a240a9a62","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80630.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-80630"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2525457"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80630"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80630"},{"url":"https://kernelcve.org/list/?q=CVE-2026-80630"},{"url":"https://lore.kernel.org/linux-cve-announce/2026082838-CVE-2026-80630-9d99@gregkh/T"}],"tags":["nvd","cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00755,"epssPercentile":0.54916,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T19:19:03.830771Z"},"scores":{"nvd":9.8,"vendor":5.5},"ingestedAt":"2026-08-29T23:43:56.447Z","slug":"CVE-2026-80630","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen\n\nWhenever fq_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 be\nexecuted even though fq_codel still has 1 packet on the queue and, thus,\nwill mistakenly deactivate the parent's class causing issues like a recent\nreport [1] and a wild memory access in qfq:\n\n[   29.371146][  T360] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI\n[   29.371666][  T360] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]\n[   29.371987][  T360] CPU: 6 UID: 0 PID: 360 Comm: tc Not tainted 7.1.0-rc5-00285-gc530e5b2dbc6-dirty #82 PREEMPT(full)\n[   29.372384][  T360] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[   29.372620][  T360] 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[   29.373544][  T360] RSP: 0018:ffff888102417370 EFLAGS: 00010216\n[   29.373800][  T360] RAX: 0000000000000000 RBX: ffff88811224d568 RCX: dffffc0000000000\n[   29.374079][  T360] RDX: 1ffff11021fe1543 RSI: ffff88810ff0aa00 RDI: dffffc0000000000\n[   29.374368][  T360] RBP: ffff88811224c280 R08: dead000000000122 R09: 1bd5a00000000024\n[   29.374649][  T360] R10: fffffbfff7940329 R11: fffffbfff7940329 R12: 0000000000000000\n[   29.374926][  T360] R13: dead000000000100 R14: ffff88811224d580 R15: ffff88811224d578\n[   29.375207][  T360] FS:  00007f5b794e5780(0000) GS:ffff88815d1e9000(0000) knlGS:0000000000000000\n[   29.375545][  T360] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[   29.375823][  T360] CR2: 000055ffb091f000 CR3: 000000010a305000 CR4: 0000000000750ef0\n[   29.376103][  T360] PKRU: 55555554\n[   29.376258][  T360] Call Trace:\n[   29.376401][  T360]  <TASK>\n...\n[   29.376885][  T360] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq\n[   29.377074][  T360]  qdisc_reset (net/sched/sch_generic.c:1057)\n[   29.377414][  T360]  __qdisc_destroy (net/sched/sch_generic.c:1096)\n[   29.377600][  T360]  qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159)\n[   29.378593][  T360]  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.\n\n[1] http://lore.kernel.org/netdev/CAN2cbVe79oj0O9==m4+4x3v+O+qzRagA=2=wkrp9i9=CqYvyZA@mail.gmail.com/\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80630.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}