Buffer overflow in Linux Kernel
CVE-2021-22555
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
Vulnerability class: Buffer Overflow
EPSS: 0.852 (99.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.3 (High). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.
Affected products
- N/a Linux Kernel — versions 2.6.19-rc1
Weakness classification (CWE)
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
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.
Public proof-of-concept exploits
References
- github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528 (x_refsource_MISC)
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter… (x_refsource_MISC)
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter… (x_refsource_MISC)
- packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-… (x_refsource_MISC)
- security.netapp.com/advisory/ntap-20210805-0010/ (x_refsource_CONFIRM)
- packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080… (x_refsource_MISC)
- packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081… (x_refsource_MISC)
- packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Writ… (x_refsource_MISC)
- packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083… (x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-22555?
- CVE-2021-22555 is a high-severity vulnerability in Linux Kernel, classified under Out-of-bounds Write. CVSS score: 8.3/10. Published 2021-07-07.
- How severe is CVE-2021-22555?
- High severity. CVSS v3 base score is 8.3 out of 10.
- Is CVE-2021-22555 known to be exploited?
- Yes. CVE-2021-22555 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-10-06), indicating it is being actively exploited. 124 public proof-of-concept repositories are indexed.