CVE-2021-3715

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-03-02 · updated 2026-06-17
Weakness: CWE-416

Description

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 kernel: from 3.18 before 4.4.218; from 4.5 before 4.9.218; from 4.10 before 4.14.175; from 4.15 before 4.19.114; from 4.20 before 5.4.29; from 5.5.0 before 5.5.14 — fixed in 4.14.175, 4.19.114, 4.4.218, 4.9.218, 5.4.29, 5.5.14

How to fix

Upgrade to a fixed version: Linux kernel 4.14.175, 4.19.114, 4.4.218, 4.9.218. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2021-3715 or the next vulnerability affects your stack