CVE-2026-73299Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer
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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.
- CVSS
- 10.0 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- Weakness (CWE)
- CWE-94, CWE-1336
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Aug 12, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
microsoft prompty microsoft:prompty (from the name) | before 0.1.5; from 2.0.0-alpha.1, < 2.0.0-beta.5 | CNA record |
References
- https://github.com/microsoft/prompty/security/advisories/GHSA-w28w-gp39-m4p6x-refsource-confirm
- https://github.com/microsoft/prompty/pull/404x-refsource-misc
- https://github.com/microsoft/prompty/pull/405x-refsource-misc
- https://github.com/microsoft/prompty/commit/e4a0ebf49e3a78d5d7796c8480bf9a4f0c54d19ex-refsource-misc
- https://github.com/microsoft/prompty/commit/f5c57c94a0990cca79d095c3daab661b4b1fb89fx-refsource-misc
- https://github.com/microsoft/prompty/tree/typescript/2.0.0-beta.5x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.