CVE-2026-49402 Deno: Command Injection via spawnSync & spawn on Windows

What is CVE-2026-49402?

CVE-2026-49402 is a high-severity command injection vulnerability in denoland deno, published on 23 Jun 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. Prior to 2.7.10, Deno's node:child_process implementation provided an escapeShellArg() helper used when callers passed shell: true to spawn / spawnSync / exec and friends. On Windows, the helper failed to quote arguments that contained cmd.exe metacharacters and did not neutralize % (which cmd.exe expands even inside double-quoted strings). An attacker who controlled any portion of an argument passed to such a call could inject arbitrary additional commands into the spawned cmd.exe invocation. This vulnerability is fixed in 2.7.10.

Weakness: CWE-78

Which versions are affected by CVE-2026-49402?

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

Products include Deno Deno.

How do I fix CVE-2026-49402?

Upgrade deno to 2.7.10 or later.

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

Is CVE-2026-49402 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49402 exists.

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-7xh3-mhg9-jcw8, JLSEC-2026-656.