MCPA-2026-0046
highrce-vectors
Prompty TypeScript loader executes JavaScript frontmatter in .prompty files (CVE-2026-53597)
The TypeScript Prompty loader (@prompty/core) used gray-matter without disabling executable frontmatter engines, so a .prompty file with a ---js frontmatter block executes arbitrary JavaScript during prompt loading. Any application loading attacker-controlled prompt assets is exposed. Affects the @prompty/core npm 2.0 prerelease line (>= 2.0.0-alpha.1); fixed in 2.0.0-beta.3.
Affected packages
| Ecosystem | Package | Affected versions |
|---|---|---|
| npm | @prompty/core | >= 2.0.0-alpha.1, < 2.0.0-beta.3 |
Identifiers
CVE-2026-53597GHSA-c4gh-rv8h-q9vwCWE-94
References
- advisory https://github.com/advisories/GHSA-c4gh-rv8h-q9vw
- advisory https://github.com/microsoft/prompty/security/advisories/GHSA-c4gh-rv8h-q9vw
- web https://nvd.nist.gov/vuln/detail/CVE-2026-53597
Timeline
- Published: 2026-07-17