{"id":"CVE-2026-72036","state":"PUBLISHED","title":"net/sched: sch_multiq: Replace direct dequeue call with peek and qdisc_dequeue_peeked","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_multiq: Replace direct dequeue call with peek and qdisc_dequeue_peeked\n\nmultiq_dequeue() takes a packet from a band's child with a direct\n->dequeue() call after multiq_peek() peeked it. When the child is\nnon-work-conserving the peek stashes the skb in the child's gso_skb, so\nthe direct dequeue returns a different skb and orphans the stash,\ndesyncing the child's qlen/backlog. With a qfq child reached through a\npeeking parent (e.g. tbf) this re-enters the child on an emptied list and\ndereferences NULL, panicking the kernel from softirq on ordinary egress.\n\nTake the packet through qdisc_dequeue_peeked(), as sch_prio already does\nand as sch_red and sch_sfb were just fixed to do. The helper is a no-op\nwhen the child has no stash, so a work-conserving child is unaffected.","publishedAt":"2026-08-15T05:51:57.012Z","updatedAt":"2026-10-19T21:19:24.167Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"3e5fd9d14f2d228e7260251f2e4a1d41ba8f705a","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"eb1a9637f0bd84b5db8803af65dfb1f44785406f","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"7a5a1582710981ef6637de9f074a60a5b1d63222","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"86a61e46a1919e8abf4d227c204773dabb24068a","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"1b9cc255e8089606b92b2adf504e334573682821","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"5889064919a1e5c0a9469c54895000414fc46944","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"fffeb2ab5eeb823d4c2330571a098f63237c9049","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"54f6b0c843e228d499eb4b6bbb89df68cad9ad5d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_multiq.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.29","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.29","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_multiq.c"]}],"references":["https://git.kernel.org/stable/c/3e5fd9d14f2d228e7260251f2e4a1d41ba8f705a","https://git.kernel.org/stable/c/eb1a9637f0bd84b5db8803af65dfb1f44785406f","https://git.kernel.org/stable/c/7a5a1582710981ef6637de9f074a60a5b1d63222","https://git.kernel.org/stable/c/86a61e46a1919e8abf4d227c204773dabb24068a","https://git.kernel.org/stable/c/1b9cc255e8089606b92b2adf504e334573682821","https://git.kernel.org/stable/c/5889064919a1e5c0a9469c54895000414fc46944","https://git.kernel.org/stable/c/fffeb2ab5eeb823d4c2330571a098f63237c9049","https://git.kernel.org/stable/c/54f6b0c843e228d499eb4b6bbb89df68cad9ad5d"],"weaknesses":["CWE-476"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72036.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72036","state":"PUBLISHED","datePublished":"2026-08-15T05:51:57.012Z","dateUpdated":"2026-10-19T21:19:24.167Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.901Z"},"containers":{"cna":{"title":"net/sched: sch_multiq: Replace direct dequeue call with peek and qdisc_dequeue_peeked","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_multiq: Replace direct dequeue call with peek and qdisc_dequeue_peeked\n\nmultiq_dequeue() takes a packet from a band's child with a direct\n->dequeue() call after multiq_peek() peeked it. When the child is\nnon-work-conserving the peek stashes the skb in the child's gso_skb, so\nthe direct dequeue returns a different skb and orphans the stash,\ndesyncing the child's qlen/backlog. With a qfq child reached through a\npeeking parent (e.g. tbf) this re-enters the child on an emptied list and\ndereferences NULL, panicking the kernel from softirq on ordinary egress.\n\nTake the packet through qdisc_dequeue_peeked(), as sch_prio already does\nand as sch_red and sch_sfb were just fixed to do. The helper is a no-op\nwhen the child has no stash, so a work-conserving child is unaffected."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"3e5fd9d14f2d228e7260251f2e4a1d41ba8f705a","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"eb1a9637f0bd84b5db8803af65dfb1f44785406f","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"7a5a1582710981ef6637de9f074a60a5b1d63222","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"86a61e46a1919e8abf4d227c204773dabb24068a","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"1b9cc255e8089606b92b2adf504e334573682821","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"5889064919a1e5c0a9469c54895000414fc46944","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"fffeb2ab5eeb823d4c2330571a098f63237c9049","versionType":"git"},{"version":"77be155cba4e163e8bba9fd27222a8b6189ec4f7","status":"affected","lessThan":"54f6b0c843e228d499eb4b6bbb89df68cad9ad5d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_multiq.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.29","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.29","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_multiq.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/3e5fd9d14f2d228e7260251f2e4a1d41ba8f705a"},{"url":"https://git.kernel.org/stable/c/eb1a9637f0bd84b5db8803af65dfb1f44785406f"},{"url":"https://git.kernel.org/stable/c/7a5a1582710981ef6637de9f074a60a5b1d63222"},{"url":"https://git.kernel.org/stable/c/86a61e46a1919e8abf4d227c204773dabb24068a"},{"url":"https://git.kernel.org/stable/c/1b9cc255e8089606b92b2adf504e334573682821"},{"url":"https://git.kernel.org/stable/c/5889064919a1e5c0a9469c54895000414fc46944"},{"url":"https://git.kernel.org/stable/c/fffeb2ab5eeb823d4c2330571a098f63237c9049"},{"url":"https://git.kernel.org/stable/c/54f6b0c843e228d499eb4b6bbb89df68cad9ad5d"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Exploitation requires locally installing a tbf→multiq→qfq hierarchy on a multiqueue netdev via RTM_NEWQDISC/tc netlink before egress can hit multiq_dequeue(); per kernel CNA guidance, tc/qdisc configuration bugs are Local even though the panic fires from softirq during packet transmission.\nAC:L - Once the hierarchy exists, the peek/dequeue mismatch is a deterministic logic bug: tbf peek stashes the QFQ child's skb in gso_skb, then multiq_dequeue's direct child->dequeue() bypasses that stash and re-enters QFQ on an emptied list; ping reproducers for sch_red/sfb show no race or layout dependency.\nPR:L - RTM_NEWQDISC and qdisc grafting are gated by netlink_net_capable(skb, CAP_NET_ADMIN) in rtnetlink_rcv_msg, evaluated against net->user_ns; unprivileged users obtain CAP_NET_ADMIN via user/network namespaces (unshare -Urn) without init-namespace root.\nUI:N - No victim interaction is needed after qdisc setup; triggering the NULL dereference requires only attacker-generated egress traffic (e.g., ping) through the defective tbf→multiq→qfq dequeue path.\nS:U - The qlen/backlog desync, orphaned gso_skb stash, and resulting kernel panic occur entirely within the host kernel packet scheduler; no VM, IOMMU, or sandbox security boundary is crossed.\nC:H - Peek stashes the skb in the non-work-conserving child's gso_skb while direct dequeue returns a different packet, desyncing qlen/backlog—the same scheduler-accounting corruption primitive seen in prior net/sched CVEs and capable of exposing corrupted or freed kernel scheduler memory.\nI:H - Orphaning the gso_skb stash corrupts parent/child queue linkage and QFQ aggregate scheduling state; inconsistent qlen drives invalid list operations in qfq_dequeue, yielding attacker-influenced memory corruption beyond the demonstrated NULL dereference.\nA:H - The desync re-enters QFQ on an emptied aggregate list and dereferences NULL in qfq_dequeue from softirq during ordinary egress, panicking the kernel as documented in the fix commit and matching KASAN null-ptr-deref traces in the related sch_red/sch_sfb reports."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:39:39.361Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.29","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.29","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.29","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.29","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.29","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.29","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.29","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.29","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-72036","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:50:31.248558Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-476","lang":"en","type":"CWE","description":"CWE-476 NULL Pointer Dereference"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T21:19:24.167Z"}}]}}}