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CVE-2026-22864

HIGH

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

Published January 16, 2026Updated February 3, 2026Source: osv

Summary

### 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.

Remediation

Upgrade to the fixed version using your package manager.

Cargo
Update deno to 2.5.6 or later
cargo update -p deno --precise 2.5.6

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (1)

PackageEcosystemAffectedFixed In
deno
crates.io
All versions2.5.6

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.1 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

References

Frequently Asked Questions

What is CVE-2026-22864?
Deno has an incomplete fix for command-injection prevention on Windows — case-insensitive extension bypass This vulnerability has been assigned a severity rating of HIGH (CVSS score: 8.1/10).
How do I check if my project is affected by CVE-2026-22864?
CVE-2026-22864 affects deno. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-22864 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
8.1

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-m3c4-prhw-mrx6

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