CVE-2026-98013

Summary

In the Linux kernel, the following vulnerability has been resolved:

net/sched: fq_pie: clamp quantum in change path

fq_pie_change() accepts any quantum value from userspace, including 1. 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().

Conditions to recreate the bug: CONFIG_NET_SCH_FQ_PIE=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices).

tc qdisc add dev dummy0 root fq_pie tc qdisc change dev dummy0 root fq_pie quantum 1 stab data 32768 size_log 15 cell_log 0

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxec97ecf1ebe485a17cd8395a5f35e6b80b57665a < f90fe65b977e7aa9eb302230a09eb18f8c32ceaaaffected
LinuxLinuxec97ecf1ebe485a17cd8395a5f35e6b80b57665a < c11e3a39807eb5a200445ae9082843ab86800415affected
LinuxLinuxec97ecf1ebe485a17cd8395a5f35e6b80b57665a < 6655b56e2801008566c594ef231f6c7b3f716c61affected
LinuxLinuxec97ecf1ebe485a17cd8395a5f35e6b80b57665a < 4864f58c53eb47257d55e01f47d4a9f355f7f970affected
LinuxLinux5.6affected
LinuxLinux0 < 5.6unaffected
LinuxLinux6.12.111 <= 6.12.*unaffected
LinuxLinux6.18.53 <= 6.18.*unaffected
LinuxLinux7.2.7 <= 7.2.*unaffected
LinuxLinux7.3-rc3 <= *unaffected

Weaknesses

References