CVE-2026-74234 MEDIUM

CVE-2026-74234: Legora < 2026-08-14 XSS via Mermaid gray-matter JavaScript Engine

Vendor Legora
Product Legora
Weakness CWE-95 · Eval injection
Published August 17, 2026
Last update August 21, 2026

CVSS base score

5.1/10
Attack vector Network
Attack complexity High
Privileges required Low
User interaction
Confidentiality
Integrity

CVSS vector

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

What the vulnerability does

01Description

Legora before 2026-08-14 contains a cross-site scripting vulnerability that allows attackers to achieve arbitrary JavaScript execution in a victim's browser by embedding a Mermaid block prefixed with a gray-matter JavaScript front-matter directive, causing the front-matter parser to invoke eval() before any SVG sanitization occurs. Attackers can exploit this flaw through influenced Mermaid diagram content to execute arbitrary JavaScript in the user's browser context, with elevated impact on Word and Outlook add-in surfaces where bearer session tokens are persisted in localStorage.

Key dates

02Disclosure timeline

August 17, 2026 CVE published
August 21, 2026 Record updated

Related vulnerabilities

04Related CVE