CVE-2026-22864
criticalpriority · track · 39EPSS 0.007 · 52 %ileEUUSEPSS · scored 2026-10-23
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8.1–9.8
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-m3c4-prhw-mrx6Deno has an incomplete fix for command-injection prevention on Windows — case-insensitive extension bypass2026-01-16ghsa · osvUS
### Summary 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.). ### POC ```javascript const command = new Deno.Command('./test.BAT', { args: ['&calc.exe'], }); const child = command.spawn(); ``` This causes `calc.exe` to be launched; see the attached screenshot for evidence. **Patched in `CVE-2025-61787` — prevents execution of `.bat` and `.cmd` files:**  **Bypass of the patched vulnerability:**  ### Impact The script launches calc.exe on Windows, demonstrating that passing user-controlled arguments to a spawned batch script can result in command-line injection. ### Mitigation Users should update to Deno v2.5.6 or newer.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (7)
External citations — patches, advisories, analysis.
- https://deno.com/Patchcnnvd
- https://github.com/denoland/deno/releases/tag/v2.5.6cnnvd
- https://github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6cnnvd
- https://github.com/denoland/deno/releases/tag/v2.5.6enisa_euvd
- https://github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6enisa_euvd
- https://github.com/denoland/deno/releases/tag/v2.5.6Release Notesnvd
- https://github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6ExploitVendor Advisorynvd
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