CVE-2026-53266

Out-of-Bounds Write in Linux Kernel. CISA confirmed attackers exploit it and added it to its Known Exploited Vulnerabilities catalog on 18 September 2026.

Product
Linux Kernel
Added to CISA's catalog
Federal fix-by date
Ransomware
No known use in ransomware campaigns

CISA’s description.

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.

Every flaw CISA confirmed exploited in the last 30 days is on the exploit watch. This is not security advice. Check the vendor’s advisory before acting. From CISA’s catalog of 4 November 2026.