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

What is CVE-2026-22864?

CVE-2026-22864 is a high-severity command injection vulnerability in denoland deno, published on 15 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-77

Which versions are affected by CVE-2026-22864?

2 open source packages ship an affected version, including deno. It affects 1 product.

Products include Deno Deno.

How do I fix CVE-2026-22864?

Upgrade deno to 2.5.6 or later.

Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.

Is CVE-2026-22864 being exploited?

There is no known exploitation of CVE-2026-22864 in the wild and no public exploit code.

Other vulnerabilities in denoland deno

• CVE-2023-28445 Deno improperly handles resizable ArrayBuffer Critical 10.0
• CVE-2022-24783 Sandbox bypass leading to arbitrary code execution in Deno Critical 10.0
• CVE-2021-32619 Static imports inside dynamically imported modules do not adhere to permission checks Critical 9.8
• CVE-2026-22863 Deno node:crypto doesn't finalize cipher Critical 9.2
• CVE-2024-27936 Deno interactive permission prompt spoofing via improper ANSI stripping High 8.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-m3c4-prhw-mrx6, JLSEC-2026-115.