CVE-2026-22864: Deno

Critical severity, CVSS 9.8. EPSS: 0.7% chance of exploitation in the next 30 days.

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Before 2.5.6, a prior patch aimed to block spawning Windows batch/shell files by returning an error when a spawned path’s extension matched .bat or .cmd. That check performs a case-sensitive comparison against lowercase literals and therefore can be bypassed when the extension uses alternate casing (for example .BAT, .Bat, etc.). This vulnerability is fixed in 2.5.6.

Affected products

• Deno Deno: before 2.5.6 (fixed in 2.5.6)

Published 2026-01-15. Last modified 2026-06-17.