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CVE-2026-43496— net/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked

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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于sch_red qdisc直接调用子qdisc的dequeue而非peek和qdisc_dequeue_peeked，可能导致空指针取消引用。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 77be155cba4e163e8bba9fd27222a8b6189ec4f7< 03b0aaeba082ae981a0dfe96cdd03d02050537a1 affected
77be155cba4e163e8bba9fd27222a8b6189ec4f7< c7335f4dc0fa21f7015b910c6fc2f4d599732328 affected
77be155cba4e163e8bba9fd27222a8b6189ec4f7< 45cd83c5c470ba49fe261489c8358ad7b9df7c45 affected
77be155cba4e163e8bba9fd27222a8b6189ec4f7< 36aa34f42cb6842cf371f3a2d3e855d24fd57a50 affected
77be155cba4e163e8bba9fd27222a8b6189ec4f7< ce051eede433f876d322ac3550a36a3c6fc4c231 affected
77be155cba4e163e8bba9fd27222a8b6189ec4f7< 8d09618840b99ef00154d3e731ce9b11e096196d affected
77be155cba4e163e8bba9fd27222a8b6189ec4f7< 587dcf970a525f543d8b5855d9f37a4ca97b76ef affected
77be155cba4e163e8bba9fd27222a8b6189ec4f7< 458d5615272d3de535748342eb68ca492343048c affected
… +10 more rows
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I. Basic Information for CVE-2026-43496

Vulnerability Information
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Vulnerability Title
net/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked When red qdisc has children (eg qfq qdisc) whose peek() callback is qdisc_peek_dequeued(), we could get a kernel panic. When the parent of such qdiscs (eg illustrated in patch #3 as tbf) wants to retrieve an skb from its child (red in this case), it will do the following: 1a. do a peek() - and when sensing there's an skb the child can offer, then - the child in this case(red) calls its child's (qfq) peek. qfq does the right thing and will return the gso_skb queue packet. Note: if there wasnt a gso_skb entry then qfq will store it there. 1b. invoke a dequeue() on the child (red). And herein lies the problem. - red will call the child's dequeue() which will essentially just try to grab something of qfq's queue. [ 78.667668][ T363] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f] [ 78.667927][ T363] CPU: 1 UID: 0 PID: 363 Comm: ping Not tainted 7.1.0-rc1-00033-g46f74a3f7d57-dirty #790 PREEMPT(full) [ 78.668263][ T363] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 78.668486][ T363] RIP: 0010:qfq_dequeue+0x446/0xc90 [sch_qfq] [ 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 [ 78.669312][ T363] RSP: 0018:ffff88810de573e0 EFLAGS: 00010216 [ 78.669533][ T363] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 78.669790][ T363] RDX: 0000000000000009 RSI: 0000000000000004 RDI: 0000000000000048 [ 78.670044][ T363] RBP: ffff888110dc4000 R08: ffffffffb1b0885a R09: fffffbfff6ba9078 [ 78.670297][ T363] R10: 0000000000000003 R11: ffff888110e31c80 R12: 0000001880000000 [ 78.670560][ T363] R13: ffff888110dc4150 R14: ffff888110dc42b8 R15: 0000000000000200 [ 78.670814][ T363] FS: 00007f66a8f09c40(0000) GS:ffff888163428000(0000) knlGS:0000000000000000 [ 78.671110][ T363] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 78.671324][ T363] CR2: 000055db4c6a30a8 CR3: 000000010da67000 CR4: 0000000000750ef0 [ 78.671585][ T363] PKRU: 55555554 [ 78.671713][ T363] Call Trace: [ 78.671843][ T363] <TASK> [ 78.671936][ T363] ? __pfx_qfq_dequeue+0x10/0x10 [sch_qfq] [ 78.672148][ T363] ? __pfx__printk+0x10/0x10 [ 78.672322][ T363] ? srso_alias_return_thunk+0x5/0xfbef5 [ 78.672496][ T363] ? lockdep_hardirqs_on_prepare+0xa8/0x1a0 [ 78.672706][ T363] ? srso_alias_return_thunk+0x5/0xfbef5 [ 78.672875][ T363] ? trace_hardirqs_on+0x19/0x1a0 [ 78.673047][ T363] red_dequeue+0x65/0x270 [sch_red] [ 78.673217][ T363] ? srso_alias_return_thunk+0x5/0xfbef5 [ 78.673385][ T363] tbf_dequeue.cold+0xb0/0x70c [sch_tbf] [ 78.673566][ T363] __qdisc_run+0x169/0x1900 The right thing to do in #1b is to grab the skb off gso_skb queue. This patchset fixes that issue by changing #1b to use qdisc_dequeue_peeked() method instead.
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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于sch_red qdisc直接调用子qdisc的dequeue而非peek和qdisc_dequeue_peeked，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 77be155cba4e163e8bba9fd27222a8b6189ec4f7 ~ 03b0aaeba082ae981a0dfe96cdd03d02050537a1 -
Linux Linux 2.6.29 -

II. Public POCs for CVE-2026-43496

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III. Intelligence Information for CVE-2026-43496

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Patches & Fixes for CVE-2026-43496 (8)

Same Patch Batch · Linux · 2026-05-21 · 8 CVEs total

CVE-2026-43501 9.8 CRITICAL ipv6: rpl: reserve mac_len headroom when recompressed SRH grows
CVE-2026-43495 8.8 HIGH net: wwan: t7xx: validate port_count against message length in t7xx_port_enum_msg_handler
CVE-2026-43502 7.8 HIGH net/rds: handle zerocopy send cleanup before the message is queued
CVE-2026-43498 7.8 HIGH accel/ivpu: Disallow re-exporting imported GEM objects
CVE-2026-43499 7.8 HIGH rtmutex: Use waiter::task instead of current in remove_waiter()
CVE-2026-43494 7.8 HIGH net/rds: reset op_nents when zerocopy page pin fails
CVE-2026-43497 7.3 HIGH fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43496

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