Bug 2492307 (CVE-2026-53079)

Summary: CVE-2026-53079 kernel: net_sched: fix skb memory leak in deferred qdisc drops
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's networking scheduler (`net_sched`). When the network stack cleans up deferred packet lists, if the root queueing discipline (qdisc) does not implement the TCQ_F_DEQUEUE_DROPS flag, packets intended for release are not freed. This can lead to a memory leak, potentially resulting in a Denial of Service (DoS) due to resource exhaustion.
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Description OSIDB Bzimport 2026-06-24 18:04:46 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net_sched: fix skb memory leak in deferred qdisc drops

When the network stack cleans up the deferred list via qdisc_run_end(),
it operates on the root qdisc. If the root qdisc do not implement the
TCQ_F_DEQUEUE_DROPS flag the packets queue to free are never freed and
gets stranded on the child's local to_free list.

Fix this by making qdisc_dequeue_drop() aware of the root qdisc. It
fetches the root qdisc and check for the TCQ_F_DEQUEUE_DROPS flag. If
the flag is present, the packet is appended directly to the root's
to_free list. Otherwise, drop it directly as it was done before the
optimization was implemented.
Comment 1 Keith Grant 2026-06-25 18:02:49 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062406-CVE-2026-53079-1491@gregkh/T