# 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

- Page: https://www.vulneraibility.com/cve/CVE-2021-22555
- CVSS: 8.3
- Known exploited: yes, in CISA KEV since 2025-10-06; CISA due date 2025-10-27
- EPSS: 78.68%
- Public exploit code: 1 on Exploit-DB · 1 Metasploit module · 13 GitHub proofs of concept (first 2021-07-15)
- CISA SSVC: exploitation active, automatable no, technical impact total (assessed 2025-10-04)
- Weakness: CWE-787
- Also known as: GHSA-xxx5-8mvq-3528
- Published: 2021-07-07

## Affected versions

- Linux Kernel: affected >= 2.6.19-rc1 and < unspecified

A version outside these ranges is not a statement that it is unaffected.

## References

- [other] https://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528
- [other] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21
- [other] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801d
- [other] http://packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.html
- [other] https://security.netapp.com/advisory/ntap-20210805-0010/
- [other] http://packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.html
- [other] http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.html
- [other] http://packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.html
- [other] http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.html
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22555

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.