High severityOSV Advisory· Published Jan 15, 2026· Updated Jan 16, 2026
Deno has an incomplete fix for command-injection prevention on Windows — case-insensitive extension bypass
CVE-2026-22864
Description
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 packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
denocrates.io | < 2.5.6 | 2.5.6 |
Affected products
1Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
4- github.com/advisories/GHSA-m3c4-prhw-mrx6ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-22864ghsaADVISORY
- github.com/denoland/deno/releases/tag/v2.5.6ghsax_refsource_MISCWEB
- github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6ghsax_refsource_CONFIRMWEB
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