CVE-2026-45553

NiceGUI versions 2.22.0 to 3.4.1 have an unsafe implementation in the pushstate event listener used by ui.sub_pages, allowing an attacker to manipulate the fragment identifier of the URL, even cross-site, using an iframe. This issue has been patched in version 3.5.0.

NiceGUI is a Python-based UI framework. Prior to version 3.12.0, two FastAPI routes that serve per-component static assets in NiceGUI accept a sub-path parameter that may resolve to a directory rather than a file. Requests that resolve to a directory raise an unhandled RuntimeError inside Starlette's FileResponse, which Uvicorn writes to the server log as a full traceback. Because the routes are reachable without authentication, a remote attacker can amplify log volume and consume disk and log-pipeline capacity on any publicly reachable NiceGUI server. This issue has been patched in version 3.12.0.

NiceGUI, a Python-based UI framework, prior to version 3.10.0 is vulnerable to arbitrary file write on Windows. Because PurePosixPath only recognizes forward slashes (/) as path separators, an attacker can bypass sanitization by using backslashes (\) in the upload filename.

NiceGUI is a Python-based UI framework. Versions 3.3.1 and below are subject to an XSS vulnerability through the ui.interactive_image component, which renders SVG content using Vue's v-html directive without any sanitization. An attacker can inject malicious HTML or JavaScript via the SVG <foreignObject> tag whenever the image component is rendered or updated.

NiceGUI, a Python-based UI framework, versions 2.24.2 and below are at risk for Cross-Site Scripting (XSS) when developers render unescaped user input into the DOM using ui.html(). Lack of HTML or JavaScript sanitization allows attackers to execute arbitrary JavaScript in the user's browser. Applications that do not pass untrusted input into ui.html() are not affected. This issue is fixed in version 3.0.0.