CVE-2026-53597 HIGH

CVE-2026-53597: Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader

Vendor Microsoft

Product prompty

Weakness CWE-94 · Code injection

Published July 16, 2026

Last update July 18, 2026

View on NVD All CVEs

CVSS base score

8.7/10

Attack vector Network

Attack complexity Low

Privileges required None

User interaction —

Confidentiality —

Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

What the vulnerability does

01Description

Prompty is a markdown file format (.prompty) for LLM prompts. From 2.0.0-alpha.1 until 2.0.0-beta.3, the @prompty/core TypeScript loader in runtime/typescript/packages/core/src/core/loader.ts used gray-matter without overriding executable js and javascript frontmatter engines, allowing an attacker-controlled .prompty file with ---js frontmatter to execute arbitrary JavaScript during prompt loading. This issue is fixed in version 2.0.0-beta.3.

Key dates

02Disclosure timeline

July 16, 2026 CVE published

July 18, 2026 Record updated

External resources

03References

NVD — National Vulnerability Database https://nvd.nist.gov/vuln/detail/CVE-2026-53597 CWE — Common Weakness Enumeration https://cwe.mitre.org/data/definitions/94.html AskarLabs — CWE-94 write-up Code Injection

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