CVE-2021-3715: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.4% chance of exploitation in the next 30 days.

A flaw was found in the "Routing decision" classifier in the Linux kernel's Traffic Control networking subsystem in the way it handled changing of classification filters, leading to a use-after-free condition. This flaw allows unprivileged local users to escalate their privileges on the system. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Affected products

• Linux Linux Kernel: from 3.18, before 4.4.218 (fixed in 4.4.218); from 4.5, before 4.9.218 (fixed in 4.9.218); from 4.10, before 4.14.175 (fixed in 4.14.175); from 4.15, before 4.19.114 (fixed in 4.19.114); from 4.20, before 5.4.29 (fixed in 5.4.29); from 5.5.0, before 5.5.14 (fixed in 5.5.14)

Published 2022-03-02. Last modified 2026-06-17.