CVE-2021-22555: Linux Kernel Heap Out-of-Bounds Write Vulnerability

High severity, CVSS 7.8. Actively exploited: in CISA KEV since 2025-10-06. EPSS: 78.7% chance of exploitation in the next 30 days.

A heap out-of-bounds write affecting Linux since v2.6.19-rc1 was discovered in net/netfilter/x_tables.c. This allows an attacker to gain privileges or cause a DoS (via heap memory corruption) through user name space

Affected products

Brocade Fabric Operating System: affected versions not specified
Linux Linux Kernel: from 2.6.19, before 4.4.267 (fixed in 4.4.267); from 4.5, before 4.9.267 (fixed in 4.9.267); from 4.10, before 4.14.231 (fixed in 4.14.231); from 4.15, before 4.19.188 (fixed in 4.19.188); from 4.20, before 5.4.113 (fixed in 5.4.113); from 5.5, before 5.10.31 (fixed in 5.10.31); …
Netapp Aff 500f Firmware: affected versions not specified
Netapp Aff a250 Firmware: affected versions not specified
Netapp Aff a400 Firmware: affected versions not specified
Netapp c250 Firmware: affected versions not specified
Netapp c400 Firmware: affected versions not specified
Netapp Cloud Backup: affected versions not specified
Netapp Fas 8300 Firmware: affected versions not specified
Netapp Fas 8700 Firmware: affected versions not specified
Netapp h300s Firmware: affected versions not specified
Netapp h410c Firmware: affected versions not specified
Netapp h410s Firmware: affected versions not specified
Netapp h500s Firmware: affected versions not specified
Netapp h610c Firmware: affected versions not specified
Netapp h610s Firmware: affected versions not specified
Netapp h615c Firmware: affected versions not specified
Netapp h700s Firmware: affected versions not specified
Netapp Hci Management Node: affected versions not specified
Netapp Solidfire: affected versions not specified
Netapp Solidfire Baseboard Management Controller: any version

Published 2021-07-07. Last modified 2026-06-17.