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CVE-2026-80630— net/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

以下是该漏洞描述的中文翻译： 在 Linux 内核中，以下漏洞已得到修复： net/sched: sch_fq_codel：不要在恢复 qlen 之前调用 qdisc_tree_reduce_backlog 当 fq_codel 在 peek（窥视）过程中丢弃数据包时，它会调用 。问题在于，它在重新增加（reincrements） 之前就调用了 。如果 降为零，但 peek 返回了一个 skb，父级的 回调函数将会被执行，尽管 fq_codel 队列中实际上还剩余 1 个数据包。这会导致父级队列节点被错误地置为不活

CVSS 9.8 · Critical EPSS 0.18% · P7

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 29

VendorProduct Version RangeStatus
Linux Linux cc71a757da78dd4aa1b4a9b19cb011833730ccf2< 3e515188393e62a718ccebee651ee74514104ff6 affected
eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450< 20dd591d8f951e1e6aca5052be8785e6181055e2 affected
829c49b6b2ff45b043739168fd1245e4e1a91a30< 94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80 affected
2f9761a94bae33d26e6a81b31b36e7d776d93dc1< acc08a0c7f37ebb1901144e03a7cba7d4afd9203 affected
4d55144b12e742404bb3f8fee6038bafbf45619d< 7c09843fd2b44d9bf0de798683861d1aecd62a08 affected
342debc12183b51773b3345ba267e9263bdfaaef< 0500af8630c3253f0dde879bd3a73a06bb2f2b3f affected
342debc12183b51773b3345ba267e9263bdfaaef< af54df2f44d9605614bc7ed96640302a240a9a62 affected
342debc12183b51773b3345ba267e9263bdfaaef< 097f6fc7b1ae362dd7a9444b2572162fda73b284 affected
… +21 more rows
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I. Basic Information for CVE-2026-80630

Vulnerability Information
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Vulnerability Title
net/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen Whenever fq_codel drops packets during peek, it calls qdisc_tree_reduce_backlog. An issue arises because it calls qdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops to zero, but peek returns an skb, the parent's qlen_notify callback will be executed even though fq_codel still has 1 packet on the queue and, thus, will mistakenly deactivate the parent's class causing issues like a recent report [1] and a wild memory access in qfq: [ 29.371146][ T360] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI [ 29.371666][ T360] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127] [ 29.371987][ T360] CPU: 6 UID: 0 PID: 360 Comm: tc Not tainted 7.1.0-rc5-00285-gc530e5b2dbc6-dirty #82 PREEMPT(full) [ 29.372384][ T360] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 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 [ 29.373544][ T360] RSP: 0018:ffff888102417370 EFLAGS: 00010216 [ 29.373800][ T360] RAX: 0000000000000000 RBX: ffff88811224d568 RCX: dffffc0000000000 [ 29.374079][ T360] RDX: 1ffff11021fe1543 RSI: ffff88810ff0aa00 RDI: dffffc0000000000 [ 29.374368][ T360] RBP: ffff88811224c280 R08: dead000000000122 R09: 1bd5a00000000024 [ 29.374649][ T360] R10: fffffbfff7940329 R11: fffffbfff7940329 R12: 0000000000000000 [ 29.374926][ T360] R13: dead000000000100 R14: ffff88811224d580 R15: ffff88811224d578 [ 29.375207][ T360] FS: 00007f5b794e5780(0000) GS:ffff88815d1e9000(0000) knlGS:0000000000000000 [ 29.375545][ T360] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.375823][ T360] CR2: 000055ffb091f000 CR3: 000000010a305000 CR4: 0000000000750ef0 [ 29.376103][ T360] PKRU: 55555554 [ 29.376258][ T360] Call Trace: [ 29.376401][ T360] <TASK> ... [ 29.376885][ T360] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq [ 29.377074][ T360] qdisc_reset (net/sched/sch_generic.c:1057) [ 29.377414][ T360] __qdisc_destroy (net/sched/sch_generic.c:1096) [ 29.377600][ T360] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159) [ 29.378593][ T360] tc_get_qdisc (net/sched/sch_api.c:1528 net/sched/sch_api.c:1556) Fix this by only calling qdisc_tree_reduce_backlog in peek after the qlen is restored. [1] http://lore.kernel.org/netdev/CAN2cbVe79oj0O9==m4+4x3v+O+qzRagA=2=wkrp9i9=CqYvyZA@mail.gmail.com/
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux cc71a757da78dd4aa1b4a9b19cb011833730ccf2 ~ 3e515188393e62a718ccebee651ee74514104ff6 -
Linux Linux 6.15 -

II. Public POCs for CVE-2026-80630

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III. Intelligence Information for CVE-2026-80630

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Patches & Fixes for CVE-2026-80630 (8)

Same Patch Batch · Linux · 2026-08-28 · 135 CVEs total

CVE-2026-80634 9.8 CRITICAL netfilter: flowtable: avoid num_encaps underflow on bridge VLAN untag
CVE-2026-80694 9.8 CRITICAL net: ethernet: mtk_eth_soc: pass eth to mtk_handle_irq_rx in poll_controller
CVE-2026-80681 9.8 CRITICAL vxlan: re-fetch eth header after route_shortcircuit()
CVE-2026-80674 9.8 CRITICAL ntfs: validate resident attribute lists and harden the validator
CVE-2026-80673 9.8 CRITICAL ntfs: bound the look-ahead attribute-list entry in ntfs_external_attr_find()
CVE-2026-80668 9.8 CRITICAL netfilter: nf_conntrack_expect: use conntrack GC to reap expectations
CVE-2026-80617 9.8 CRITICAL net: airoha: fix foe_check_time allocation size
CVE-2026-80612 9.8 CRITICAL net: lwtunnel: Drop skb metadata before LWT encapsulation
CVE-2026-80714 9.8 CRITICAL ipvs: do not propagate one-packet flag to synced conns
CVE-2026-80609 9.8 CRITICAL qede: fix out-of-bounds check for cqe->len_list[]
CVE-2026-80600 9.8 CRITICAL batman-adv: dat: acquire ARP hw source only after skb realloc
CVE-2026-80693 9.3 CRITICAL idpf: bound interrupt-vector register fill to the allocated array
CVE-2026-80684 9.3 CRITICAL KVM: s390: pci: Fix NULL dereference on AIBV allocation failure
CVE-2026-80671 9.3 CRITICAL perf sched: Fix register_pid() overflow, strcpy, and BUG_ON
CVE-2026-80603 9.1 CRITICAL netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read
CVE-2026-80670 9.1 CRITICAL perf tools: Use perf_env__get_cpu_topology() in machine__resolve()
CVE-2026-80721 8.8 HIGH Bluetooth: ISO: ensure no dangling hcon references in iso_conn
CVE-2026-80722 8.8 HIGH wifi: mac80211: validate individual TWT params before driver setup
CVE-2026-80724 8.8 HIGH ptp: vmclock: prevent read-only mappings from becoming writable
CVE-2026-80683 8.8 HIGH Bluetooth: SCO: give the socket its own sco_conn reference

Showing top 20 of 135 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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