CVE-2026-22864

HighPublic PoCRCE

Published: 15 January 2026

Published

15 January 2026

Modified

21 January 2026

KEV Added

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Patch

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

EPSS Score 0.0003 8.9th percentile

Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-22864 is a high-severity Command Injection (CWE-77) vulnerability in Deno Deno. Its CVSS base score is 8.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Windows Command Shell (T1059.003); ranked at the 8.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and CM-6 (Configuration Settings).

Threat & Defense at a Glance

What attackers do: exploitation maps to Windows Command Shell (T1059.003). What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Directly requires identification, reporting, and timely patching of flaws like the case-sensitive extension check bypass in Deno prior to version 2.5.6 to prevent command injection.

RA-5 Vulnerability Monitoring and Scanning partial match

detect

Provides vulnerability scanning to detect systems running vulnerable Deno versions exploitable via mixed-case batch file extensions.

CM-6 Configuration Settings partial match

prevent

Ensures secure configuration settings for runtimes like Deno, including enforcement of patched versions that fix the Windows-specific spawning bypass.

MITRE ATT&CK Enterprise TechniquesAI

T1059.003 Windows Command Shell Execution

Adversaries may abuse the Windows command shell for execution.

attack.mitre.org →

Why these techniques?

Bypass of .bat/.cmd extension block in Deno spawn APIs directly enables execution of Windows batch/shell files (command injection).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Before 2.5.6, 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.). This vulnerability is fixed in 2.5.6.

Deeper analysisAI

CVE-2026-22864 is a vulnerability in Deno, a JavaScript, TypeScript, and WebAssembly runtime, affecting versions prior to 2.5.6 on Windows systems. A previous patch intended to prevent spawning of batch or shell files by blocking paths with .bat or .cmd extensions used a case-sensitive comparison against lowercase literals, allowing bypass via alternate casing such as .BAT or .Bat. This issue, classified under CWE-77 (Command Injection), carries a CVSS v3.1 base score of 8.1 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H).

The vulnerability can be exploited by remote attackers requiring no privileges or user interaction, though it demands high attack complexity, likely due to crafting a suitable path with mixed-case extensions in Deno's process spawning APIs. Successful exploitation enables spawning arbitrary Windows batch or shell files, resulting in high-impact confidentiality, integrity, and availability violations, potentially leading to full system compromise within the Deno runtime environment.

Mitigation is provided in Deno version 2.5.6, which addresses the case-sensitivity flaw in the extension check. Official advisories recommend upgrading to this version, as detailed in the Deno release notes at https://github.com/denoland/deno/releases/tag/v2.5.6 and the security advisory at https://github.com/denoland/deno/security/advisories/GHSA-m3c4-prhw-mrx6.