Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-22555

CVE-2021-22555HIGH

n/a Linux Kernel — Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   L   L   N  U  H  H  H    7.8   .7868   99.6   YES

AFFECTED
  Product       Versions      Fixed
  Linux Kernel  2.6.19-rc1 –  —

TIMELINE
  Jan 5   Reserved by Google
  Jul 7   Published (CNA: Google)
  Oct 6   Added to CISA KEV, remediation due 2025-10-27
  Oct 13  EXPLOIT PUBLISHED — CVE-2021-22555 (Linux Kernel). Public exploit reference added.
  Oct 13  RESCORED — CVE-2021-22555 (Linux Kernel). CVSS 8.3 → 7.8 (NVD).

CWE-787 · CNA: Google · CVSS v3.1 · 10 references · NVD status: Analyzed · KEV due October 27, 2025

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

Lifecycle

Complete event history — 5 events, chronological
Date	Event	Detail
January 5, 2021	Reserved	Reserved by Google
July 7, 2021	Published	Published (CNA: Google)
October 6, 2025	KEV ADDED	Added to CISA KEV, remediation due 2025-10-27
October 13, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2021-22555 (Linux Kernel). Public exploit reference added.
October 13, 2026	RESCORED	RESCORED — CVE-2021-22555 (Linux Kernel). CVSS 8.3 → 7.8 (NVD).

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
n/a	Linux Kernel	—	2.6.19-rc1	—

Weaknesses

CWE-787

References (10)

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

Authoritative record: CVE-2021-22555 at cve.org

Weaknesses: CWE-787

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-22555 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.