CVE-2021-22555VulnerabilityPublished 10/06/2025Updated 10/24/2026
CVE-2021-22555: Linux Kernel Heap Out-of-Bounds Write Vulnerability
Affects Linux KernelSource CISA KEV
Severity
HighNo CVSS score published yet
- Exploitation
Actively exploited – in CISA KEV since 10/06/2025
- KEV deadline
- 10/27/2025
- EPSS
- 78.7% chance of exploitation in 30 days – higher than 99% of CVEs
What to do
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.
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21 (opens in a new tab)
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801d (opens in a new tab)
- security.netapp.com/advisory/ntap-20210805-0010/ (opens in a new tab)
- github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2021-22555 (opens in a new tab)
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.
Weaknesses
References
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21 (opens in a new tab)
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801d (opens in a new tab)
- security.netapp.com/advisory/ntap-20210805-0010/ (opens in a new tab)
- github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2021-22555 (opens in a new tab)
- cisa.gov/known-exploited-vulnerabilities-catalog?search=CVE-2021-22555 (opens in a new tab)