CVE-2021-22555
KEVLinux Kernel Heap Out-of-Bounds Write Vulnerability
Description
Linux Kernel contains a heap out-of-bounds write vulnerability that could allow an attacker to gain privileges or cause a DoS (via heap memory corruption) through user name space.
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 vector
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:HPublishedJul 7, 2021
Last modifiedOct 13, 2026
Added to KEVOct 6, 2025
Remediation dueOct 27, 2025
References
- packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.htmlThird Party AdvisoryVDB Entry
- packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.htmlExploitThird Party Advisory
- packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.htmlExploitThird Party Advisory
- packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.htmlExploitThird Party Advisory
- packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlExploitThird Party Advisory
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21Mailing ListPatch
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801dMailing ListPatch
- github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528ExploitThird Party Advisory
- security.netapp.com/advisory/ntap-20210805-0010/Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22555US Government Resource
0 recent articles mention this CVE
79
Risk assessment · High
Actively exploited. Patch immediately.
- Exploitation
- Confirmed in the wild (CISA KEV)
- Federal remediation deadline
- Overdue by 366 days
- CVSS
- 8.3 HIGH
- EPSS (30-day exploit probability)
- 78.7% · top 1% of all CVEs
- Weakness
- CWE-787
- Preconditions
- No privileges and no user interaction
Recommended actions
- 1.Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- 2.Treat as emergency change: patch or isolate internet-facing instances first.
- 3.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
Assessment is derived automatically from the live signals above; verify against your own asset inventory.