October 6, 2025 · Applied Cybernetics Group
CVE-2021-22555 Linux Kernel
Linux Kernel Heap Out-of-Bounds Write Vulnerability
- Added to KEV
2025-10-06- Federal due date
2025-10-27- Vendor
- Linux
- Product
- Kernel
- EPSS
- 99.6th percentile (score 0.787, as of
2026-11-06) - NVD CVSS v3.1
- 8.3 (HIGH)
- Ransomware use
- Unknown
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2021-22555
CISA short 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.
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.
NVD 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