CVE-2026-73299CWE-1336CWE-94code-injection

CVE-2026-73299

Critical · published August 12, 2026

CVSS v3.1
10.0
EPSS
2%
Percentile
78.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
10.0 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.01784 · 78.1th percentile
Weaknesses
CWE-1336 · Improper Neutralization of Special Elements Used in a Template Engine; CWE-94 · Improper Control of Generation of Code ('Code Injection')
Published
2026-08-12T22:18Z
References (6)
https://github.com/microsoft/prompty/commit/e4a0ebf49e3a78d5d7796c8480bf9a4f0c54d19e · [email protected]https://github.com/microsoft/prompty/commit/f5c57c94a0990cca79d095c3daab661b4b1fb89f · [email protected]https://github.com/microsoft/prompty/pull/404 · [email protected]https://github.com/microsoft/prompty/pull/405 · [email protected]https://github.com/microsoft/prompty/security/advisories/GHSA-w28w-gp39-m4p6 · [email protected]https://github.com/microsoft/prompty/tree/typescript/2.0.0-beta.5 · [email protected]
EPSS history
Timeline
  • 12 AUG 17:31Z
    Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer
    cvelistv5