Medium [CVE-2026-72036] Replace direct dequeue call with peek and qdisc_dequeue_peeked
This medium-severity Red Hat Linux advisory covers CVE-2026-72036 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
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.
A flaw was found in the Linux kernel's `sch_multiq` component, which handles network packet scheduling. This vulnerability occurs when a non-work-conserving child queue is improperly handled after a packet has been temporarily stored.
This can lead to a desynchronization of network packet queues and a null pointer dereference. An attacker could exploit this by sending specially crafted network traffic, causing the kernel to panic and resulting in a Denial of Service (DoS).
Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-476.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 25 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 25 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 25 days ago·verify at source
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