CVE-2025-40083: Linux

EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_qfq: Fix null-deref in agg_dequeue To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c) when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return value before using it, similar to the existing approach in sch_hfsc.c. To avoid code duplication, the following changes are made: 1. Changed qdisc_warn_nonwc(include/net/pkt_sched.h) into a static inline function. 2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to include/net/pkt_sched.h so that sch_qfq can reuse it. 3. Applied qdisc_peek_len in agg_dequeue to avoid crashing.

Affected products

• Linux Linux: from 3.8, before 5.4.302 (fixed in 5.4.302); from 5.5, before 5.10.247 (fixed in 5.10.247); from 5.11, before 5.15.197 (fixed in 5.15.197); from 5.16, before 6.1.159 (fixed in 6.1.159); from 6.2, before 6.6.116 (fixed in 6.6.116); from 6.7, before 6.12.57 (fixed in 6.12.57); …

Published 2025-10-29. Last modified 2026-06-17.