CVE-2025-68325: In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_cake: Fix incorrect qlen reduction in cake_drop In cake_drop(), q...

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_cake: Fix incorrect qlen reduction in cake_drop In cake_drop(), qdisc_tree_reduce_backlog() is used to update the qlen and backlog of the qdisc hierarchy. Its caller, cake_enqueue(), assumes that the parent qdisc will enqueue the current packet. However, this assumption breaks when cake_enqueue() returns NET_XMIT_CN: the parent qdisc stops enqueuing current packet, leaving the tree qlen/backlog accounting inconsistent. This mismatch can lead to a NULL dereference (e.g., when the parent Qdisc is qfq_qdisc). This patch computes the qlen/backlog delta in a more robust way by observing the difference before and after the series of cake_drop() calls, and then compensates the qdisc tree accounting if cake_enqueue() returns NET_XMIT_CN. To ensure correct compensation when ACK thinning is enabled, a new variable is introduced to keep qlen unchanged.

Metrics

EPSS Probability

0.18%

7.8th percentile

Probability of exploitation in the next 30 days. Learn more

References

Timeline

Published: Dec 18, 2025
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2025-68325?

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_cake: Fix incorrect qlen reduction in cake_drop In cake_drop(), qdisc_tree_reduce_backlog() is used to update the qlen and backlog of the qdisc hierarchy. Its caller, cake_enqueue(), assumes that the parent qdisc will enqueue the current packet. However, this assumption breaks when cake_enqueue() returns NET_XMIT_CN: the parent qdisc stops enqueuing current packet, leaving the tree qlen/backlog accounting inconsistent. This mismatch can lead to a NULL dereference (e.g., when the parent Qdisc is qfq_qdisc). This patch computes the qlen/backlog delta in a more robust way by observing the difference before and after the series of cake_drop() calls, and then compensates the qdisc tree accounting if cake_enqueue() returns NET_XMIT_CN. To ensure correct compensation when ACK thinning is enabled, a new variable is introduced to keep qlen unchanged.

How severe is CVE-2025-68325?

Severity scoring for CVE-2025-68325 is pending analysis. The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.

How do I fix CVE-2025-68325?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.