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Advisories

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

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severity
medium
date
Affecting

  • Legora < 2026-08-14

CWE
  • CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
CVSS
5.1
CVSS V4 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
Credit
Mobasi Security Team
Description
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.

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