Linux Kernel Heap Out-of-Bounds Write Vulnerability
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
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 3 / 5
- KEV catalog (CISA)06 Oct 2025
- Exploited in EUVD (ENISA)06 Oct 2025
- Used by ransomwareno
- EPSS above 10 %78.7%
- No account, over the networkno
What to do
Fix
Update to a fixed version: 5.10.38-1
CISA guidance: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Affected products
- 2.6.19-rc1 <unspecified
Open source packages OSV
- linuxDebian:12 · CVE-2021-22555fixed in 5.10.38-1
- linuxDebian:13 · CVE-2021-22555fixed in 5.10.38-1
Timeline
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Published
-
Exploitation reported (ENISA)
-
Added to the KEV catalog
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CISA remediation due date
-
EPSS peak: 78.7%
References
Other exploited vulnerabilities from the same vendor
- CVE-2026-46300Linux Kernel Missing Initialization of a Variable Vulnerability5.4 · Rising fast
- CVE-2026-53266Linux Kernel Out-of-Bounds Write Vulnerability4.7 · Actively exploited
- CVE-2025-39964Linux Kernel Race Condition Vulnerability4.4 · Actively exploited
- CVE-2025-39682Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability5.8 · Actively exploited
- CVE-2026-53362Linux Kernel Unspecified Vulnerability4.3 · Actively exploited
- CVE-2022-0995Linux Kernel Out-of-Bounds Write Vulnerability4.6 · Actively exploited