{"id":"CVE-2026-43496","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked\n\nWhen red qdisc has children (eg qfq qdisc) whose peek() callback is\nqdisc_peek_deque…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked\n\nWhen red qdisc has children (eg qfq qdisc) whose peek() callback is\nqdisc_peek_deque…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-476"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 2.6.29, < 5.10.258","linux_kernel >= 5.11, < 5.15.209","linux_kernel >= 5.16, < 6.1.175","linux_kernel >= 6.2, < 6.6.140","linux_kernel >= 6.7, < 6.12.88","linux_kernel >= 6.13, < 6.18.30","linux_kernel >= 6.19, < 7.0.7","linux_kernel = 7.1"],"patched":["linux_kernel 7.0.7"],"published":"2026-05-21","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:19:34.233","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-43496","references":[{"url":"https://git.kernel.org/stable/c/03b0aaeba082ae981a0dfe96cdd03d02050537a1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/36aa34f42cb6842cf371f3a2d3e855d24fd57a50","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/458d5615272d3de535748342eb68ca492343048c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/45cd83c5c470ba49fe261489c8358ad7b9df7c45","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/587dcf970a525f543d8b5855d9f37a4ca97b76ef","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8d09618840b99ef00154d3e731ce9b11e096196d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c7335f4dc0fa21f7015b910c6fc2f4d599732328","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ce051eede433f876d322ac3550a36a3c6fc4c231","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00162,"epssPercentile":0.05053,"ingestedAt":"2026-10-15T03:30:12.875Z","slug":"CVE-2026-43496","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked\n\nWhen red qdisc has children (eg qfq qdisc) whose peek() callback is\nqdisc_peek_dequeued(), we could get a kernel panic. When the parent of such\nqdiscs (eg illustrated in patch #3 as tbf) wants to retrieve an skb from\nits child (red in this case), it will do the following:\n 1a. do a peek() - and when sensing there's an skb the child can offer, then\n     - the child in this case(red) calls its child's (qfq) peek.\n        qfq does the right thing and will return the gso_skb queue packet.\n        Note: if there wasnt a gso_skb entry then qfq will store it there.\n 1b. invoke a dequeue() on the child (red). And herein lies the problem.\n     - red will call the child's dequeue() which will essentially just\n       try to grab something of qfq's queue.\n\n[   78.667668][  T363] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]\n[   78.667927][  T363] CPU: 1 UID: 0 PID: 363 Comm: ping Not tainted 7.1.0-rc1-00033-g46f74a3f7d57-dirty #790 PREEMPT(full)\n[   78.668263][  T363] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[   78.668486][  T363] RIP: 0010:qfq_dequeue+0x446/0xc90 [sch_qfq]\n[   78.668718][  T363] Code: 54 c0 e8 dd 90 00 f1 48 c7 c7 e0 03 54 c0 48 89 de e8 ce 90 00 f1 48 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <80> 3c 02 00 74 05 e8 ef a1 e1 f1 48 8b 7b 48 48 8d 54 24 58 48 8d\n[   78.669312][  T363] RSP: 0018:ffff88810de573e0 EFLAGS: 00010216\n[   78.669533][  T363] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000\n[   78.669790][  T363] RDX: 0000000000000009 RSI: 0000000000000004 RDI: 0000000000000048\n[   78.670044][  T363] RBP: ffff888110dc4000 R08: ffffffffb1b0885a R09: fffffbfff6ba9078\n[   78.670297][  T363] R10: 0000000000000003 R11: ffff888110e31c80 R12: 0000001880000000\n[   78.670560][  T363] R13: ffff888110dc4150 R14: ffff888110dc42b8 R15: 0000000000000200\n[   78.670814][  T363] FS:  00007f66a8f09c40(0000) GS:ffff888163428000(0000) knlGS:0000000000000000\n[   78.671110][  T363] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[   78.671324][  T363] CR2: 000055db4c6a30a8 CR3: 000000010da67000 CR4: 0000000000750ef0\n[   78.671585][  T363] PKRU: 55555554\n[   78.671713][  T363] Call Trace:\n[   78.671843][  T363]  <TASK>\n[   78.671936][  T363]  ? __pfx_qfq_dequeue+0x10/0x10 [sch_qfq]\n[   78.672148][  T363]  ? __pfx__printk+0x10/0x10\n[   78.672322][  T363]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   78.672496][  T363]  ? lockdep_hardirqs_on_prepare+0xa8/0x1a0\n[   78.672706][  T363]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   78.672875][  T363]  ? trace_hardirqs_on+0x19/0x1a0\n[   78.673047][  T363]  red_dequeue+0x65/0x270 [sch_red]\n[   78.673217][  T363]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   78.673385][  T363]  tbf_dequeue.cold+0xb0/0x70c [sch_tbf]\n[   78.673566][  T363]  __qdisc_run+0x169/0x1900\n\nThe right thing to do in #1b is to grab the skb off gso_skb queue.\nThis patchset fixes that issue by changing #1b to use qdisc_dequeue_peeked()\nmethod instead.\n\n## Affected\n\n- `linux_kernel >= 2.6.29, < 5.10.258`\n- `linux_kernel >= 5.11, < 5.15.209`\n- `linux_kernel >= 5.16, < 6.1.175`\n- `linux_kernel >= 6.2, < 6.6.140`\n- `linux_kernel >= 6.7, < 6.12.88`\n- `linux_kernel >= 6.13, < 6.18.30`\n- `linux_kernel >= 6.19, < 7.0.7`\n- `linux_kernel = 7.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.7`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}