Critical severity · published Jan 15, 2026
CVE-2026-22864
Deno has an incomplete fix for command-injection prevention on Windows — case-insensitive extension bypass
9.8
CVSS
0.7%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 52% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DE
deno · denoland
< 2.5.6 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-22864
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-22864
Release Notes
https://github.com/denoland/deno/releases/tag/v2.5.6
Exploit
https://github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6
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