CVE-2026-73299 CRITICAL

CVE-2026-73299: Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer

Vendor Microsoft
Product prompty
Weakness CWE-94 · Code injection
Published August 12, 2026
Last update August 12, 2026
View on NVD All CVEs

CVSS base score

10.0/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 0.1.5 and 2.0.0-beta.5, the TypeScript Nunjucks renderer evaluated untrusted .prompty template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process. This issue is fixed in versions 0.1.5 and 2.0.0-beta.5.

Key dates

02Disclosure timeline

August 12, 2026 CVE published

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