Deno: Command Injection via spawnSync & spawn on Windows

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.1 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-49402: 0.45% estimated exploitation activity in the next 30 days; percentile 38.72 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Deno's node:childprocess 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 such as &, |, <, , ^, !, (, ), 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 was the Windows counterpart to CVE-2026-27190, which fixed the same class of bug in the Unix branch of escapeShellArg. Details On Windows, childprocess with shell: true ran the command via cmd.exe /d /s /c "<command line". Deno assembled that command line by joining the program name and each argument through escapeShellArg(). The vulnerable check was: The regex covered only whitespace, double-quote, and backslash. Any argument containing cmd.exe-significant characters…

Published by the source

16 Jun 2026, 19:07 UTC

Last modified by the source

20 Jul 2026, 21:01 UTC

Source last checked

26 Oct 2026, 15:43 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-7xh3-mhg9-jcw8

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-49402

Advisory: Deno: Command Injection via spawnSync & spawn on Windows
IDs: CVE-2026-49402, GHSA-7xh3-mhg9-jcw8
Record: https://patchnext.com/advisories/cve-2026-49402 (revision 1, source checked 26 Oct 2026, 15:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: deno 2.7.10. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io deno: affected < 2.7.10; fixed in 2.7.10

## Suggested inspection (read-only)
- crates.io deno: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on deno.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-7xh3-mhg9-jcw8 (GitHub-reviewed advisory GHSA-7xh3-mhg9-jcw8 lists affected ranges: crates.io deno >=0 <2.7.10)

Commands are suggestions: review each one before running it.