Linux Kernel Heap Out-of-Bounds Write Vulnerability
n/a — Linux Kernel
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
8.3
78.7%
Vector breakdown
- Attack vector
- Adjacent
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- Published
- Jul 7, 2021
- Modified
- Oct 13, 2026
- Added to KEV
- Oct 6, 2025
- Federal patch due
- Oct 27, 2025
CISA required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Weakness classification
Proof-of-concept & exploitation references
8 foundWeaponization
Public repositories whose name or description references CVE-2021-22555, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit - cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
- veritas501/CVE-2021-22555-PipeVersion★ 40
CVE-2021-22555 exploit rewritten with pipe primitive
updated May 18, 2026
- xyjl-ly/CVE-2021-22555-Exploit★ 14
CVE-2021-22555 Exploit
updated May 28, 2026
- cgwalters/container-cve-2021-22555★ 4
updated Dec 1, 2021
- tukru/CVE-2021-22555★ 3
This repo hosts TUKRU's Linux Privilege Escalation exploit (CVE-2021-22555). It demonstrates gaining root privileges via a vulnerability. Tested on Ubuntu 5.8.0-48-generic and COS 5.4.89+. Use responsibly and ethically.
updated Sep 5, 2024
- JoneyJunior/cve-2021-22555★ 1
updated Feb 16, 2022
- Spydomain/CVE-2021-22555-Poc★ 1
updated Mar 6, 2026
- daletoniris/CVE-2021-22555-esc-priv★ 1
updated Mar 3, 2026
- masjohncook/netsec-project★ 1
Script of Network Security Project - Attack on CVE-2021-22555
updated Jun 6, 2023
References
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
How severe is CVE-2021-22555?
CVE-2021-22555 has a CVSS base score of 8.3 out of 10 (CVSS 3.1).
Is CVE-2021-22555 actively exploited in the wild?
Yes. CVE-2021-22555 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added Oct 6, 2025, meaning CISA has confirmed evidence of active exploitation.
What is the EPSS score for CVE-2021-22555?
78.7% - meaning FIRST.org's EPSS model estimates a 78.7% probability this vulnerability will be exploited in the wild within 30 days (100% percentile among all scored CVEs).
Is there exploit tooling available for CVE-2021-22555?
We found 8 public GitHub repositories referencing CVE-2021-22555, though none matched a known Nuclei template or Metasploit module at last check. Review each one before relying on it - see the proof-of-concept section above.
What type of vulnerability is CVE-2021-22555?
CVE-2021-22555 is classified under CWE-787 (CWE-787 Out-of-bounds Write).
Cross-checked against
Impactr finds and proves whether CVE-2021-22555 - or flaws like it - are actually reachable in your own web apps and APIs, with a reproducible exploit as evidence.
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