CVE-2026-72036 net/sched: sch_multiq: Replace direct dequeue call with peek and qdisc_dequeue_peeked
A null pointer dereference in the Linux kernel's multiq scheduler can cause a kernel panic during packet egress, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72036?
CVE-2026-72036 is a high-severity vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_multiq: Replace direct dequeue call with peek and qdisc_dequeue_peeked
multiq_dequeue() takes a packet from a band's child with a direct ->dequeue() call after multiq_peek() peeked it. When the child is non-work-conserving the peek stashes the skb in the child's gso_skb, so the direct dequeue returns a different skb and orphans the stash, desyncing the child's qlen/backlog. With a qfq child reached through a peeking parent (e.g. tbf) this re-enters the child on an emptied list and dereferences NULL, panicking the kernel from softirq on ordinary egress.
Take the packet through qdisc_dequeue_peeked(), as sch_prio already does and as sch_red and sch_sfb were just fixed to do. The helper is a no-op when the child has no stash, so a work-conserving child is unaffected.
Weakness: CWE-476
Which versions are affected by CVE-2026-72036?
How do I fix CVE-2026-72036?
Apply the vendor's patch.
Is CVE-2026-72036 being exploited?
There is no known exploitation of CVE-2026-72036 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72036, DEBIAN-CVE-2026-72036, GHSA-6mv6-43g2-7qmw, UBUNTU-CVE-2026-72036.