Actively exploited
Listed in CISA’s Known Exploited Vulnerabilities catalog since September 18, 2026.
CVE-2026-53266
Linux Kernel Out-of-Bounds Write Vulnerability
Added to KEV September 18, 2026
Alert details
- Source feed
- CISA KEV
- CVE ID
- CVE-2026-53266
- CWE
- CWE-787
- Affected products
- Kernel · Linux Kernel · Linux
What happened
Linux Kernel contains an out-of-bounds write vulnerability in the ebtables SNAT target which allows an ARP sender hardware address rewrite to write directly into a nonlinear socket-buffer fragment backed by a splice-imported file page. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.
What it means for your business
Linux Kernel is listed in CISA's Known Exploited Vulnerabilities catalog (CVE-2026-53266). Linux Kernel contains an out-of-bounds write vulnerability in the ebtables SNAT target which allows an ARP sender hardware address rewrite to write directly into a nonlinear socket-buffer fragment backed by a splice-imported file page. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version. CISA remediation due date: 2026-09-21. If you need help checking exposure, call (864) 335-9223.
Required action
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
CISA due date: September 21, 2026
Sources
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