CVE-2021-22555

Linux Kernel

Published 7 Jul 2021 · updated 17 Jun 2026 · Analyzed

7.8 High · CVSS 3.1, NVD

Exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on 6 Oct 2025, with a remediation deadline of 27 Oct 2025 for US federal agencies.

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.

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

References

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