CVE-2021-22555
Linux Kernel Heap Out-of-Bounds Write Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 27 October 2025). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 78.68% probability · 100th percentile
- Public exploits
- 1 in Exploit-DB · verified · first 15 July 2021
- CISA KEV
- Listed 6 October 2025 · due 27 October 2025
- Weakness
- CWE-787
- Affected
- netapp/c400 firmware · netapp/c250 firmware · netapp/h410c firmware · netapp/h300s firmware · netapp/h500s firmware · netapp/h700s firmware · netapp/h410s firmware · linux/linux kernel · broadcom/fabric operating system · netapp/fas 8300 firmware · netapp/fas 8700 firmware · netapp/aff a400 firmware · netapp/aff a250 firmware · netapp/aff 500f firmware · netapp/h610c firmware · netapp/h610s firmware · netapp/h615c firmware · netapp/cloud backup · netapp/hci management node · netapp/solidfire · +1 more
- Source
- cve-coordination@google.com
EPSS 78.7% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. 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://security.netapp.com/advisory/ntap-20210805-0010/ ; https://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528 ; https://nvd.nist.gov/vuln/detail/CVE-2021-22555
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- http://packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.htmlThird Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlExploit, Third Party Advisory, VDB Entry
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21Mailing List, Patch, Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801dMailing List, Patch, Vendor Advisory
- https://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528Exploit, 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.htmlThird Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlExploit, Third Party Advisory, VDB Entry
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21Mailing List, Patch, Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801dMailing List, Patch, Vendor Advisory
- https://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528Exploit, 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-2021-22555US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.