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CVE-2026-74266— net/sched: sch_dualpi2: 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.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.17版本存在安全漏洞，该漏洞源于在peek期间丢弃数据包时，在恢复qlen之前调用qdisc_tree_reduce_backlog，可能导致空指针取消引用。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.21% · P10

Possible ATT&CK Techniques 1 AI

T1498.002 · Reflection Amplification

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 8f9516daedd67097a0c6e463fcb7a42b5ee9d477< bd851b10daee7199a658458b8ce250e95a334500 affected
8f9516daedd67097a0c6e463fcb7a42b5ee9d477< 466f29477cae2bd1982a066d518a9b20c5a37924 affected
8f9516daedd67097a0c6e463fcb7a42b5ee9d477< 15cd0c93bf4f892d66bc7a93667e2357b5673365 affected
6.17 affected
< 6.17 unaffected
6.18.40≤ 6.18.* unaffected
7.1.5≤ 7.1.* unaffected
7.2≤ * unaffected
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I. Basic Information for CVE-2026-74266

Vulnerability Information
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Vulnerability Title
net/sched: sch_dualpi2: 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_dualpi2: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen Whenever dualpi2 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 dualpi2 still has 1 packet on the queue and, thus, mistakenly deactivates the parent's class which leads to a null-ptr-deref: [ 101.427314][ T599] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN NOPTI [ 101.427755][ T599] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f] [ 101.428048][ T599] CPU: 2 UID: 0 PID: 599 Comm: ping Not tainted 7.1.0-rc5-00284-gbce53c430ed7 #102 PREEMPT(full) [ 101.428400][ T599] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 101.428608][ T599] RIP: 0010:qfq_dequeue (net/sched/sch_qfq.c:1150) sch_qfq [ 101.428821][ T599] Code: 00 fc ff df 80 3c 02 00 0f 85 46 0c 00 00 4c 8d 73 48 48 89 9d b8 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 2d 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b All code [ 101.429348][ T599] RSP: 0018:ffff8881110df4f0 EFLAGS: 00010216 [ 101.429541][ T599] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000 [ 101.429763][ T599] RDX: 0000000000000009 RSI: 00000024c0000000 RDI: ffff88811436c2b0 [ 101.429985][ T599] RBP: ffff88811436c000 R08: ffff88811436c280 R09: 1ffff11021277523 [ 101.430206][ T599] R10: 1ffff11021277526 R11: 1ffff11021277527 R12: 00000024c0000000 [ 101.430423][ T599] R13: ffff88811436c2b8 R14: 0000000000000048 R15: 0000000020000000 [ 101.430642][ T599] FS: 00007f61813e1c40(0000) GS:ffff8881691ef000(0000) knlGS:0000000000000000 [ 101.430913][ T599] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 101.431100][ T599] CR2: 00005651650850a8 CR3: 000000010ca0b000 CR4: 0000000000750ef0 [ 101.431320][ T599] PKRU: 55555554 [ 101.431433][ T599] Call Trace: [ 101.431544][ T599] <TASK> [ 101.431628][ T599] __qdisc_run (net/sched/sch_generic.c:322 net/sched/sch_generic.c:427 net/sched/sch_generic.c:445) [ 101.431792][ T599] ? dev_qdisc_enqueue (./include/trace/events/qdisc.h:49 (discriminator 22) net/core/dev.c:4176 (discriminator 22)) [ 101.431941][ T599] __dev_queue_xmit (./include/net/pkt_sched.h:120 ./include/net/pkt_sched.h:117 net/core/dev.c:4292 net/core/dev.c:4831) Fix this by only calling qdisc_tree_reduce_backlog in peek after the qlen is restored.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.17版本存在安全漏洞，该漏洞源于在peek期间丢弃数据包时，在恢复qlen之前调用qdisc_tree_reduce_backlog，可能导致空指针取消引用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 8f9516daedd67097a0c6e463fcb7a42b5ee9d477 ~ bd851b10daee7199a658458b8ce250e95a334500 -
Linux Linux 6.17 -

II. Public POCs for CVE-2026-74266

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III. Intelligence Information for CVE-2026-74266

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Patches & Fixes for CVE-2026-74266 (3)

Same Patch Batch · Linux · 2026-08-15 · 844 CVEs total

CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72319 9.8 CRITICAL ipvs: ensure inner headers in ICMP errors are in headroom
CVE-2026-72220 9.8 CRITICAL sunrpc: harden rq_procinfo lifecycle to prevent double-free
CVE-2026-72217 9.8 CRITICAL SUNRPC: Bound-check xdr_buf_to_bvec() stores before writing
CVE-2026-74384 9.8 CRITICAL nvme-multipath: fix flex array size in struct nvme_ns_head
CVE-2026-72299 9.8 CRITICAL tipc: restrict socket queue dumps in enqueue tracepoints
CVE-2026-72210 9.8 CRITICAL ntfs: fix off-by-one in mapping pairs decoding bounds checks
CVE-2026-72211 9.8 CRITICAL ntfs: grow index root value before reparent header update
CVE-2026-72317 9.8 CRITICAL SUNRPC: pin upper rpc_clnt across the TLS connect_worker
CVE-2026-72209 9.8 CRITICAL ntfs: validate attribute values on lookup
CVE-2026-74268 9.8 CRITICAL tcp: clear sock_ops cb flags before force-closing a child socket
CVE-2026-72207 9.8 CRITICAL ntfs: not change 0-byte $DATA attribute to non-resident
CVE-2026-74267 9.8 CRITICAL net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring q

Showing top 20 of 844 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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