CVE-2026-22864

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.

Score

CVSS 3.1 9.8 Critical

Status

Analyzed - security-advisories@github.com

Published

2026-01-15

Last modified

2026-01-16

Weaknesses

CWE-77

Affected products

• Deno (Deno)
• Deno (Denoland)

References

• https://github.com/denoland/deno/releases/tag/v2.5.6
• https://github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6