CVE-2026-73299
CriticalCVSS 10.0Exploitation Probability (EPSS)
Elevated risk67th percentile - higher than 67% of all known CVEs
Summary
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.
Risk Assessment
The risk for the organization is remote code execution in the Node.js process, which can lead to application and data compromise.
Recommendation
It is recommended to update Prompty to version 0.1.5 or 2.0.0-beta.5 and avoid processing untrusted .prompty files.
Other vulnerabilities in Prompty
See all- 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.
- CVE-2026-53597High
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.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS