CVE-2026-25516
MEDIUM
GHSA-v82v-c5x8-w282
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Lifecycle Timeline
4Description
NiceGUI is a Python-based UI framework. The ui.markdown() component uses the markdown2 library to convert markdown content to HTML, which is then rendered via innerHTML. By default, markdown2 allows raw HTML to pass through unchanged. This means that if an application renders user-controlled content through ui.markdown(), an attacker can inject malicious HTML containing JavaScript event handlers. Unlike other NiceGUI components that render HTML (ui.html(), ui.chat_message(), ui.interactive_image()), the ui.markdown() component does not provide or require a sanitize parameter, leaving applications vulnerable to XSS attacks. This vulnerability is fixed in 3.7.0.
Analysis
Cross-site scripting in NiceGUI's ui.markdown() component allows unauthenticated attackers to inject malicious HTML and JavaScript into applications that render user-controlled markdown content, as the component lacks built-in sanitization unlike other NiceGUI HTML rendering functions. Public exploit code exists for this vulnerability affecting NiceGUI versions before 3.7.0. …
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Remediation
Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.
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External POC / Exploit Code
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