CVE-2021-33033: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.6% chance of exploitation in the next 30 days.

The Linux kernel before 5.11.14 has a use-after-free in cipso_v4_genopt in net/ipv4/cipso_ipv4.c because the CIPSO and CALIPSO refcounting for the DOI definitions is mishandled, aka CID-ad5d07f4a9cd. This leads to writing an arbitrary value.

Affected products

• Linux Linux Kernel: from 2.6.28, before 4.9.298 (fixed in 4.9.298); from 4.10, before 4.14.226 (fixed in 4.14.226); from 4.15, before 4.19.181 (fixed in 4.19.181); from 4.20, before 5.4.106 (fixed in 5.4.106); from 5.5, before 5.10.24 (fixed in 5.10.24); from 5.11, before 5.11.7 (fixed in 5.11.7)

Published 2021-05-14. Last modified 2026-08-05.