GHSA-W28W-GP39-M4P6
Vulnerability from github – Published: 2026-07-24 16:23 – Updated: 2026-07-24 16:23Summary
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.
Affected packages
- npm
@prompty/coreversions<= 0.1.4 - npm
@prompty/coreversions<= 2.0.0-beta.4
Impact
Applications that render untrusted, community-supplied, cloned, or LLM-generated .prompty files with the TypeScript runtime could allow attacker-controlled code execution with the privileges of the Node.js host process.
Remediation
Upgrade to @prompty/core 2.0.0-beta.5 or later. The patched renderer sanitizes render inputs to own-data-only values, rejects constructor/prototype member traversal, and disallows template function calls. Ordinary interpolation, conditionals, loops, and own nested data properties remain supported.
Fix details
The fix is merged in PR #404 and includes regression coverage for default Nunjucks rendering, explicit renderer usage, unsafe member lookups, and attempted template function calls.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.1.4"
},
"package": {
"ecosystem": "npm",
"name": "@prompty/core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.1.5"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.0.0-beta.4"
},
"package": {
"ecosystem": "npm",
"name": "@prompty/core"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0-alpha.1"
},
{
"fixed": "2.0.0-beta.5"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-1336",
"CWE-94"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-24T16:23:59Z",
"nvd_published_at": null,
"severity": "CRITICAL"
},
"details": "## Summary\nThe 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.\n\n## Affected packages\n- npm `@prompty/core` versions `\u003c= 0.1.4`\n- npm `@prompty/core` versions `\u003c= 2.0.0-beta.4`\n\n## Impact\nApplications that render untrusted, community-supplied, cloned, or LLM-generated `.prompty` files with the TypeScript runtime could allow attacker-controlled code execution with the privileges of the Node.js host process.\n\n## Remediation\nUpgrade to `@prompty/core` `2.0.0-beta.5` or later. The patched renderer sanitizes render inputs to own-data-only values, rejects constructor/prototype member traversal, and disallows template function calls. Ordinary interpolation, conditionals, loops, and own nested data properties remain supported.\n\n## Fix details\nThe fix is merged in PR #404 and includes regression coverage for default Nunjucks rendering, explicit renderer usage, unsafe member lookups, and attempted template function calls.",
"id": "GHSA-w28w-gp39-m4p6",
"modified": "2026-07-24T16:23:59Z",
"published": "2026-07-24T16:23:59Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/microsoft/prompty/security/advisories/GHSA-w28w-gp39-m4p6"
},
{
"type": "WEB",
"url": "https://github.com/microsoft/prompty/pull/404"
},
{
"type": "WEB",
"url": "https://github.com/microsoft/prompty/commit/047756f4c8caf91c5868eeb42520c938393277b0"
},
{
"type": "PACKAGE",
"url": "https://github.com/microsoft/prompty"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.