CVE-2026-53079: net_sched: fix skb memory leak in deferred qdisc drops

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-24 · updated 2026-07-23
Weakness: CWE-401

Description

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.

Affected products

Linux kernel: from 6.19 before 7.0.10 — fixed in 7.0.10

How to fix

Upgrade to a fixed version: Linux kernel 7.0.10. Check the vendor advisory for mitigations.

References

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