CVE-2026-22864: Deno Deno Has An Incomplete Fix Vulnerability

HIGH
Advisory Identifier: GHSA-m3c4-prhw-mrx6
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CVSS 8.1
CWE-77
Published
Advisory Summary

CVE-2026-22864 is a HIGH (CVSS 8.1) deno has an incomplete fix vulnerability (CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')) affecting Deno libraries in the crates.io ecosystem. The issue involves deno has an incomplete fix for command-injection prevention on windows — case-insensitive extension bypass. Remediation is available by upgrading affected packages to version 2.5.6.

CVE-2026-22864 at a Glance

CVE Identifier CVE-2026-22864
GHSA Identifier GHSA-m3c4-prhw-mrx6
Severity HIGH
CVSS v3.1 Base Score 8.1
CWE Classification CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')
Affected Product Deno
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 8.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-22864

To remediate this vulnerability, upgrade all affected Deno dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

deno fixed: 2.5.6 
Upgrade deno to 2.5.6
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for deno

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-22864, inspect your project dependencies for Deno:

inspect dependencies for deno

Analyze the terminal output to locate any version of Deno in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.5.6), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection'), where the product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component. In Deno, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary 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.). ### POC ```javascript const command = new Deno.Command('./test.BAT', { args: ['&calc.exe'], }); const child = command.spawn(); ``` This causes `calc.exe` to be launched; see the attached screenshot for evidence. **Patched in `CVE-2025-61787` — prevents execution of `.bat` and `.cmd` files:** ![photo_2025-10-10 02 27 23](https://github.com/user-attachments/assets/43df25e2-e2e1-48aa-8060-cb0a22637f1f) **Bypass of the patched vulnerability:** ![photo_2025-10-10 02 27 25](https://github.com/user-attachments/assets/2be1afb4-84a1-4883-8e18-6a174fdd3615) ### Impact The script launches calc.exe on Windows, demonstrating that passing user-controlled arguments to a spawned batch script can result in command-line injection. ### Mitigation Users should update to Deno v2.5.6 or newer.

CVE-2026-22864 Affected Deno Versions

1 component(s)
Fixed Versions:
2.5.6
Product / Package Ecosystem Affected Versions Fixed Version
deno
 crates.io
< 2.5.6
2.5.6

References

GitHub Advisory / Wiki ADVISORY
https://github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6
NVD — CVE-2026-22864 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-22864
Deno Source Repository REPOSITORY
https://github.com/denoland/deno
Deno Release RELEASE
https://github.com/denoland/deno/releases/tag/v2.5.6

Frequently Asked Questions

What is CVE-2026-22864?
CVE-2026-22864 is a security vulnerability in Deno involving Deno has an incomplete fix for command-injection prevention on Windows — case-insensitive extension bypass under CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection').
Which Deno versions are affected?
Affected versions include releases prior to 2.5.6 across affected packages: deno.
What version fixes CVE-2026-22864?
Upgrading to 2.5.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is deno affected?
Yes, deno is affected in releases prior to 2.5.6. Upgrade your dependency to 2.5.6 or later.
What is the CVSS score of CVE-2026-22864?
CVE-2026-22864 has a CVSS v3.1 base score of 8.1 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-22864?
CVE-2026-22864 is classified under CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection') (The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.).
How can I check crates.io dependencies for CVE-2026-22864?
Run the dependency tree command: 'inspect dependencies for deno'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m3c4-prhw-mrx6",
  "modified" : "2026-01-16T15:49:38Z",
  "published" : "2026-01-16T15:49:38Z",
  "aliases" : [ "CVE-2026-22864" ],
  "summary" : "Deno has an incomplete fix for command-injection prevention on Windows — case-insensitive extension bypass",
  "details" : "### Summary\nA 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.).\n\n### POC\n```javascript\nconst command = new Deno.Command('./test.BAT', {\n  args: ['&calc.exe'],\n});\nconst child = command.spawn();\n```\nThis causes `calc.exe` to be launched; see the attached screenshot for evidence.\n\n**Patched in `CVE-2025-61787` — prevents execution of `.bat` and `.cmd` files:**\n![photo_2025-10-10 02 27 23](https://github.com/user-attachments/assets/43df25e2-e2e1-48aa-8060-cb0a22637f1f)\n\n**Bypass of the patched vulnerability:**\n![photo_2025-10-10 02 27 25](https://github.com/user-attachments/assets/2be1afb4-84a1-4883-8e18-6a174fdd3615)\n\n\n### Impact\nThe script launches calc.exe on Windows, demonstrating that passing user-controlled arguments to a spawned batch script can result in command-line injection.\n\n### Mitigation\n\nUsers should update to Deno v2.5.6 or newer.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "deno"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.5.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-22864"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/denoland/deno"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/denoland/deno/releases/tag/v2.5.6"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-77" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-16T15:49:38Z",
    "nvd_published_at" : "2026-01-15T23:15:51Z"
  }
}