CVE-2026-73299: Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer
Published Aug 12, 2026
·Updated
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.
Affected Software
3 affected components
Prompty @prompty/core Nunjucks Renderer>0.1.5<2.0.0-beta.5
Prompty @prompty/core Nunjucks Renderer<0.1.5
Prompty @prompty/core Nunjucks Renderer<2.0.0-beta.5
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 0.1.5 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 2.0.0-beta.5
Event History
Aug 12, 2026
CVE Published
via MITRE·05:31 PM
Data Sourced
via MITRE·05:31 PM
DescriptionSeverityWeakness