Vulnerability-Lookup

CVE-2026-49402 (GCVE-0-2026-49402)

Vulnerability from cvelistv5 – Published: 2026-06-23 17:20 – Updated: 2026-06-25 03:55

Title

Deno: Command Injection via spawnSync & spawn on Windows

Summary

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.

Severity

8.1 (High)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-24 00:00 UTC

CWE

CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/denoland/deno/security/advisor…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
denoland	deno	Affected: < 2.7.10	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-49402

Vulnerability from fkie_nvd - Published: 2026-06-23 18:18 - Updated: 2026-06-26 17:33

Severity

8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/denoland/deno/security/advisories/GHSA-7xh3-mhg9-jcw8	Exploit, Mitigation, Vendor Advisory
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/denoland/deno/security/advisories/GHSA-7xh3-mhg9-jcw8	Exploit, Mitigation, Vendor Advisory

Impacted products

	Vendor	Product	Version
	deno	deno	*
	microsoft	windows	-

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To clipboard

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GHSA-7XH3-MHG9-JCW8

Vulnerability from github – Published: 2026-06-16 19:07 – Updated: 2026-07-20 21:01

Summary

Deno: Command Injection via spawnSync & spawn on Windows

Details

Summary

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 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, child_process 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:

// If no special characters, return as-is
if (!/[\s"\\]/.test(arg)) {
  return arg;
}

The regex covered only whitespace, double-quote, and backslash. Any argument containing cmd.exe-significant characters but none of those three was returned unquoted and therefore interpreted by the shell. The most straightforward exploit chained commands with &:

import { spawnSync } from "node:child_process";

spawnSync("echo", ["test&calc.exe"], { shell: true, encoding: "utf-8" });

The reporter confirmed this launched calc.exe on Windows 11 with Deno 2.7.5. The same shape worked for |, <, >, ^, !, (, and ).

A secondary defect existed even when arguments were quoted: cmd.exe expands %FOO% environment-variable references inside double-quoted strings. Without either doubling % or rejecting it, an argument like "%USERPROFILE%" leaked environment data into the command line.

Proof of concept

From the report, run on Windows with Deno < 2.7.10:

import { spawnSync } from "node:child_process";

const maliciousInput = "test&calc.exe";
const result = spawnSync("echo", [maliciousInput], {
  shell: true,
  encoding: "utf-8",
});
console.log(result);

Observed: calc.exe launched as a side effect of the echo call.

Impact

Any Deno program on Windows that called child_process.spawn / spawnSync / exec (or any shell helper that funneled through escapeShellArg) with shell: true and incorporated untrusted input into an argument was exposed to arbitrary command execution in the context of the Deno process. The CVSS vector treated this as network-reachable / high-complexity because the typical exposure path was a Deno service accepting external input and forwarding it to a shelled-out subprocess.

Not affected:

Calls without shell: true (the default), which executed the program directly via CreateProcess without cmd.exe interpretation.
Unix platforms, which used the single-quote branch of escapeShellArg and were already fixed under CVE-2026-27190.
Callers that built command strings themselves and passed them as a single string with shell: true — those were the caller's responsibility and were never sanitized by Deno.

Workarounds

Users on unpatched versions could mitigate by:

Avoiding shell: true in node:child_process calls on Windows.
Building the argv directly and invoking the program without a shell.
Filtering or rejecting any externally-supplied argument values that contained cmd.exe metacharacters (& | < > ^ ! ( ) %) before passing them to spawn / spawnSync / exec.

Severity

8.1 (High)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "deno"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.7.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-49402"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-78"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-16T19:07:44Z",
    "nvd_published_at": "2026-06-23T18:18:03Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nDeno\u0027s `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 such as `\u0026`, `|`, `\u003c`, `\u003e`, `^`, `!`, `(`, `)`, 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.\n\nThis was the Windows counterpart to CVE-2026-27190, which fixed the same class of bug in the Unix branch of `escapeShellArg`.\n\n## Details\n\nOn Windows, `child_process` with `shell: true` ran the command via `cmd.exe /d /s /c \"\u003ccommand line\u003e\"`. Deno assembled that command line by joining the program name and each argument through `escapeShellArg()`.\n\nThe vulnerable check was:\n\n```ts\n// If no special characters, return as-is\nif (!/[\\s\"\\\\]/.test(arg)) {\n  return arg;\n}\n```\n\nThe regex covered only whitespace, double-quote, and backslash. Any argument containing `cmd.exe`-significant characters but none of those three was returned unquoted and therefore interpreted by the shell. The most straightforward exploit chained commands with `\u0026`:\n\n```js\nimport { spawnSync } from \"node:child_process\";\n\nspawnSync(\"echo\", [\"test\u0026calc.exe\"], { shell: true, encoding: \"utf-8\" });\n```\n\nThe reporter confirmed this launched `calc.exe` on Windows 11 with Deno 2.7.5. The same shape worked for `|`, `\u003c`, `\u003e`, `^`, `!`, `(`, and `)`.\n\nA secondary defect existed even when arguments were quoted: `cmd.exe` expands `%FOO%` environment-variable references inside double-quoted strings. Without either doubling `%` or rejecting it, an argument like `\"%USERPROFILE%\"` leaked environment data into the command line.\n\n## Proof of concept\n\nFrom the report, run on Windows with Deno `\u003c 2.7.10`:\n\n```js\nimport { spawnSync } from \"node:child_process\";\n\nconst maliciousInput = \"test\u0026calc.exe\";\nconst result = spawnSync(\"echo\", [maliciousInput], {\n  shell: true,\n  encoding: \"utf-8\",\n});\nconsole.log(result);\n```\n\nObserved: `calc.exe` launched as a side effect of the `echo` call.\n\n## Impact\n\nAny Deno program on Windows that called `child_process.spawn` / `spawnSync` / `exec` (or any shell helper that funneled through `escapeShellArg`) with `shell: true` and incorporated untrusted input into an argument was exposed to arbitrary command execution in the context of the Deno process. The CVSS vector treated this as network-reachable / high-complexity because the typical exposure path was a Deno service accepting external input and forwarding it to a shelled-out subprocess.\n\nNot affected:\n\n- Calls without `shell: true` (the default), which executed the program directly via `CreateProcess` without `cmd.exe` interpretation.\n- Unix platforms, which used the single-quote branch of `escapeShellArg` and were already fixed under CVE-2026-27190.\n- Callers that built command strings themselves and passed them as a single string with `shell: true` \u2014 those were the caller\u0027s responsibility and were never sanitized by Deno.\n\n## Workarounds\n\nUsers on unpatched versions could mitigate by:\n\n- Avoiding `shell: true` in `node:child_process` calls on Windows.\n- Building the argv directly and invoking the program without a shell.\n- Filtering or rejecting any externally-supplied argument values that contained `cmd.exe` metacharacters (`\u0026 | \u003c \u003e ^ ! ( ) %`) before passing them to `spawn` / `spawnSync` / `exec`.",
  "id": "GHSA-7xh3-mhg9-jcw8",
  "modified": "2026-07-20T21:01:31Z",
  "published": "2026-06-16T19:07:44Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/denoland/deno/security/advisories/GHSA-7xh3-mhg9-jcw8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49402"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/denoland/deno"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Deno: Command Injection via spawnSync \u0026 spawn on Windows"
}

Sightings

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Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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CVE-2026-49402 (GCVE-0-2026-49402)

FKIE_CVE-2026-49402

GHSA-7XH3-MHG9-JCW8

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