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CISA KEV·Added 2025-10-06 — agencies required to remediate by 2025-10-27

CVE-2021-22555

HIGH
Also known asA-184847809PUB-A-184847809
Published
Jul 7, 2021
Updated
Mar 15, 2026
Affected
0 pkgs
Patched
None yet
Exploits
17 known

EPSS Exploitation Probability

via FIRST.org ↗
85.2%probability of exploitation in next 30 days
Very High Risk99th percentile0.00%
84.5%85.3%86.0%86.8%85.0%85.2%Dec 25Apr 26Jun 26

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

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

Exploits & PoCs
17

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-50135locallinux✓ Verified

Linux Kernel 2.6.19 < 5.9 - 'Netfilter Local Privilege Escalation

by TheFloW · Jul 15, 2021

Frequently Asked Questions

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
O3 Security · Impact-Aware SCA

Is CVE-2021-22555 in your stack?

O3 detects CVE-2021-22555 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.