# CVE-2021-22555: Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE

> CVE-2021-22555: Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE. CVSS 8.3 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2021-22555
Last updated: 2025-12-30T20:32:33Z

- Published: 2021-07-07 11:20 UTC · Updated: 2025-12-30 20:32 UTC · Assigner: Google
- CVSS: 8.3 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- EPSS: 78.7%, 100th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2025-10-06, federal due date 2025-10-27, ransomware use: Unknown
- CWE: CWE-787

## 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 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.

## Affected vendors and products

- n/a: Linux Kernel

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-22555)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2021-22555)
- [http://packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.html](http://packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.html)
- [http://packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.html](http://packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.html)
- [http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.html](http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.html)
- [http://packetstormsecurity.com/files/164437/Netfilter-x\_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.html](http://packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.html)
- [http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.html](http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.html)
- [https://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528](https://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528)
- [https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x\_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21)
- [https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x\_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801d](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801d)
- [https://security.netapp.com/advisory/ntap-20210805-0010/](https://security.netapp.com/advisory/ntap-20210805-0010/)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2021-22555 · Markdown: https://rewindex.com/cve/CVE-2021-22555.md · JSON: https://rewindex.com/api/v1/cves/CVE-2021-22555 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:16:54.171Z