{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-80630", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.776Z", "datePublished": "2026-08-28T06:48:46.569Z", "dateUpdated": "2026-10-16T19:26:31.257Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-29T06:21:30.275Z" }, "descriptions": [ { "lang": "en", "value": "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_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] \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/" } ], "metrics": [ { "cvssV3_1": { "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" }, "scenarios": [ { "lang": "en", "value": "AV:N - Remote senders reach the bug when packets traverse a QFQ or other qlen_notify parent with an fq_codel child: qfq_enqueue() and qfq_dequeue() call the child peek handler during __dev_queue_xmit egress 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 an fq_codel leaf, 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 to drive peek-time CoDel drops through the installed hierarchy; no independent action by another user or administrator is needed at trigger time.\nS:U - The flaw corrupts in-kernel QFQ/fq_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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/sch_fq_codel.c" ], "versions": [ { "version": "cc71a757da78dd4aa1b4a9b19cb011833730ccf2", "lessThan": "3e515188393e62a718ccebee651ee74514104ff6", "status": "affected", "versionType": "git" }, { "version": "eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450", "lessThan": "20dd591d8f951e1e6aca5052be8785e6181055e2", "status": "affected", "versionType": "git" }, { "version": "829c49b6b2ff45b043739168fd1245e4e1a91a30", "lessThan": "94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80", "status": "affected", "versionType": "git" }, { "version": "2f9761a94bae33d26e6a81b31b36e7d776d93dc1", "lessThan": "acc08a0c7f37ebb1901144e03a7cba7d4afd9203", "status": "affected", "versionType": "git" }, { "version": "4d55144b12e742404bb3f8fee6038bafbf45619d", "lessThan": "7c09843fd2b44d9bf0de798683861d1aecd62a08", "status": "affected", "versionType": "git" }, { "version": "342debc12183b51773b3345ba267e9263bdfaaef", "lessThan": "0500af8630c3253f0dde879bd3a73a06bb2f2b3f", "status": "affected", "versionType": "git" }, { "version": "342debc12183b51773b3345ba267e9263bdfaaef", "lessThan": "af54df2f44d9605614bc7ed96640302a240a9a62", "status": "affected", "versionType": "git" }, { "version": "342debc12183b51773b3345ba267e9263bdfaaef", "lessThan": "097f6fc7b1ae362dd7a9444b2572162fda73b284", "status": "affected", "versionType": "git" }, { "version": "7a742a9506849d1c1aa71e36c89855ceddc7d58e", "status": "affected", "versionType": "git" }, { "version": "e73c838c80dccb9e4f19becc11d9f3cb4a27d483", "status": "affected", "versionType": "git" }, { "version": "a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31", "status": "affected", "versionType": "git" }, { "version": "5.10.241", "lessThan": "5.10.261", "status": "affected", "versionType": "semver" }, { "version": "5.15.190", "lessThan": "5.15.212", "status": "affected", "versionType": "semver" }, { "version": "6.1.135", "lessThan": "6.1.178", "status": "affected", "versionType": "semver" }, { "version": "6.6.88", "lessThan": "6.6.145", "status": "affected", "versionType": "semver" }, { "version": "6.12.24", "lessThan": "6.12.97", "status": "affected", "versionType": "semver" }, { "version": "5.4.297", "lessThan": "5.5", "status": "affected", "versionType": "semver" }, { "version": "6.13.12", "lessThan": "6.14", "status": "affected", "versionType": "semver" }, { "version": "6.14.3", "lessThan": "6.15", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/sch_fq_codel.c" ], "versions": [ { "version": "6.15", "status": "affected" }, { "version": "0", "lessThan": "6.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.261", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.241", "versionEndExcluding": "5.10.261" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.190", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.135", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.88", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.24", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.2" }, { "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" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3e515188393e62a718ccebee651ee74514104ff6" }, { "url": "https://git.kernel.org/stable/c/20dd591d8f951e1e6aca5052be8785e6181055e2" }, { "url": "https://git.kernel.org/stable/c/94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80" }, { "url": "https://git.kernel.org/stable/c/acc08a0c7f37ebb1901144e03a7cba7d4afd9203" }, { "url": "https://git.kernel.org/stable/c/7c09843fd2b44d9bf0de798683861d1aecd62a08" }, { "url": "https://git.kernel.org/stable/c/0500af8630c3253f0dde879bd3a73a06bb2f2b3f" }, { "url": "https://git.kernel.org/stable/c/af54df2f44d9605614bc7ed96640302a240a9a62" }, { "url": "https://git.kernel.org/stable/c/097f6fc7b1ae362dd7a9444b2572162fda73b284" } ], "title": "net/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-80630", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:19:03.830771Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:31.257Z" } } ] } }