HIGH CISA KEV

CVE-2021-22555

CVSS v3

7.8

HIGH

EPSS Score

85.2%

exploit probability

CISA KEV

Yes

known exploited

Exploitation

SSVC status

Description

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

CISA Known Exploited Vulnerability

Date Added
10/6/2025
Patch Due Date
10/27/2025
Ransomware Use
Unknown

Technical details

Published
7/7/2021

Frequently asked questions

What is CVE-2021-22555?

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

Is CVE-2021-22555 actively exploited?

Yes. CVE-2021-22555 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 10/27/2025.

What is the CVSS score for CVE-2021-22555?

CVE-2021-22555 has a CVSS v3 base score of 7.8 (HIGH severity).

Is CVE-2021-22555 affecting your environment?

Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.