CVE-2026-22864: Deno has an incomplete fix for command-injection prevention on Windows — case-insensitive extension bypass

January 16, 2026 (updated August 28, 2026)

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.).

References

github.com/advisories/GHSA-m3c4-prhw-mrx6
github.com/denoland/deno/releases/tag/v2.5.6
github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6
nvd.nist.gov/vuln/detail/CVE-2026-22864

Code Behaviors & Features

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