CVE-2026-98012: Linux

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

In the Linux kernel, the following vulnerability has been resolved: net/sched: sfq: clamp quantum in change path sfq_change() accepts any non-negative quantum (only rejects (int)ctl->quantum < 0). With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 makes the deficit-refill loop spin ~2^31 times under the qdisc lock (a soft lockup / denial of service). Add max(256U, ...) matching fq_codel_change(). Reject quantum > 1<<20 with -EINVAL, matching fq_codel_change() and the init clamp. Conditions to recreate the bug: CONFIG_NET_SCH_SFQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root sfq tc qdisc change dev dummy0 root sfq quantum 1 stab data 32768 size_log 15 cell_log 0

Affected products

• Linux Linux: from 5.10.239, before 5.10.271 (fixed in 5.10.271); from 5.15.186, before 5.15.222 (fixed in 5.15.222); from 6.1.129, before 6.1.189 (fixed in 6.1.189); from 6.6.76, before 6.6.158 (fixed in 6.6.158); from 6.12.13, before 6.12.111 (fixed in 6.12.111); from 5.4.297, before 5.5 (fixed in 5.5); …

Published 2026-09-25. Last modified 2026-10-03.