CVE-2026-53597
HighCVSS 8.7Exploitation Probability (EPSS)
Elevated risk57th percentile - higher than 57% of all known CVEs
Summary
A vulnerability in the Prompty library allows arbitrary JavaScript execution when loading .prompty files. The TypeScript loader uses gray-matter without overriding default frontmatter engines, enabling an attacker to inject malicious code via a file with ---js frontmatter.
Risk Assessment
An attacker can remotely execute arbitrary JavaScript on the server or development environment, leading to full system compromise, data theft, or application takeover.
Recommendation
Immediately update Prompty to version 2.0.0-beta.3 or later. Before updating, do not load .prompty files from untrusted sources.
Other vulnerabilities in Prompty
See all- CVE-2026-73299Critical
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.
- CVE-2026-53598High
In Prompty prior to version 2.0.0-beta.2, the loaders expanded ${file:...} references in .prompty frontmatter without validating that resolved paths stayed within the allowed directory, allowing an attacker-controlled prompt file to read local files via absolute paths, .. traversal, or symlink escapes.
Original NVD description (English source)
Prompty is a markdown file format (.prompty) for LLM prompts. From 2.0.0-alpha.1 until 2.0.0-beta.3, the @prompty/core TypeScript loader in runtime/typescript/packages/core/src/core/loader.ts used gray-matter without overriding executable js and javascript frontmatter engines, allowing an attacker-controlled .prompty file with ---js frontmatter to execute arbitrary JavaScript during prompt loading. This issue is fixed in version 2.0.0-beta.3.