CVE-2021-22555

7.8 high KEV · due 2025-10-27 exploit ×15 SSVC exploitation: active Analyzed

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

Fix

Public exploits 15

Linux Kernel 2.6.19 < 5.9 - 'Netfilter Local Privilege Escalation (local · linux) Exploit-DB · verified · 2021-07-15
Netfilter x_tables Heap OOB Write Privilege Escalation (exploit module) Metasploit · verified · 2021-07-07
JoneyJunior/cve-2021-22555 PoC on GitHub
Spydomain/CVE-2021-22555-Poc PoC on GitHub
WhatsWrongAndWhy/CVE-2021-22555 PoC on GitHub
cgwalters/container-cve-2021-22555 PoC on GitHub
daletoniris/CVE-2021-22555-esc-priv PoC on GitHub
glutton-su/CVE-2021-22555 PoC on GitHub
letsr00t/-2021-LOCALROOT-CVE-2021-22555 PoC on GitHub
letsr00t/CVE-2021-22555 PoC on GitHub
masjohncook/netsec-project PoC on GitHub
pashayogi/CVE-2021-22555 PoC on GitHub
tukru/CVE-2021-22555 PoC on GitHub
veritas501/CVE-2021-22555-PipeVersion PoC on GitHub
xyjl-ly/CVE-2021-22555-Exploit PoC on GitHub

Each line links to the index that lists it, never to exploit code. Exploit-DB's "verified" and a Metasploit rank of good or better count as verified; a PoC-in-GitHub entry is a repository's claim.

CISA KEV required action · due 2025-10-27

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Added to the catalog 2025-10-06. CISA KEV

Patch, vendor advisory and mitigation references on NVD 4

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://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

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 1

2026-10-15 00:45First seenCVSS 7.8 · in KEV · netapp, linux, broadcomNVD modified 2026-10-13 18:25

Affected (CPE criteria) 21

cpe:2.3:o:netapp:c400_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:c250_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:broadcom:fabric_operating_system:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:fas_8300_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:fas_8700_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:aff_a400_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:aff_a250_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:aff_500f_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h610c_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h610s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h615c_firmware:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:solidfire_baseboard_management_controller:*:*:*:*:*:*:*:*

References 19

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
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