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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-73299
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-12 18:18:15 UTC
Updated2026-08-12 20:17:53 UTC
DescriptionPrompty 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 And Classification

Primary CVSS: v3.1 10 CRITICAL from [email protected]

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

Problem Types: CWE-94 | CWE-1336 | CWE-94 CWE-94: Improper Control of Generation of Code ('Code Injection') | CWE-1336 CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1CNADECLARED10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Microsoft Prompty affected < 0.1.5 Not specified
CNA Microsoft Prompty affected >= 2.0.0-alpha.1, < 2.0.0-beta.5 Not specified

References

ReferenceSourceLinkTags
github.com/microsoft/prompty/pull/405 [email protected] github.com
github.com/microsoft/prompty/commit/e4a0ebf49e3a78d5d7796c8480bf9a4f0c54... [email protected] github.com
github.com/microsoft/prompty/commit/f5c57c94a0990cca79d095c3daab661b4b1f... [email protected] github.com
github.com/microsoft/prompty/security/advisories/GHSA-w28w-gp39-m4p6 [email protected] github.com
github.com/microsoft/prompty/tree/typescript/2.0.0-beta.5 [email protected] github.com
github.com/microsoft/prompty/pull/404 [email protected] github.com
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