RCE in Deno
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.
Vulnerability class: Command Injection (OS Command Injection)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.007 (50.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 50.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.001
Affected products
- Deno
- Denoland Deno — versions < 2.5.6
Weakness classification (CWE)
References
- github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6 (Exploit, Vendor Advisory)
- github.com/denoland/deno/releases/tag/v2.5.6 (Release Notes)
Frequently asked questions
- What is CVE-2026-22864?
- CVE-2026-22864 is a high-severity vulnerability in Deno, classified under Command Injection. CVSS score: 8.1/10. Published 2026-01-15.
- How severe is CVE-2026-22864?
- High severity. CVSS v3 base score is 8.1 out of 10.