In CISA KEV8.3 HighCWE-787
CVE-2021-22555
Linux Kernel Heap Out-of-Bounds Write Vulnerability
LinuxKernel
Status
- Exploited in the wild
- In CISA KEV since 6 Oct 2025
- Vendor fix available
Federal deadlineMon 27 Oct 2025, 23:59 UTC
Passed 362 days ago
CISA KEV · added 6 Oct 2025
Exploit probabilityEPSSchecked 25 Oct
79%probability of exploitation in the next 30 days
Higher than 100% of scored CVEs
SeverityCVSS
8.3High
Description NVD
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
CISA 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.
Coverage 1 article · 1 outlet
- Office and Windows flaws boost exploit kits in Q1 2026Securelist · first in our coverage · mentions it in passing