NiceGUI vulnerabilities
4 known CVE vulnerabilities in NiceGUI, translated and rated.
- CVE-2026-21873High
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.
- CVE-2026-45554Medium
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.
- CVE-2026-45553High
NiceGUI prior to version 3.12.0 has a vulnerability in ui.restructured_text() that renders reStructuredText server-side without disabling file insertion directives. An attacker can read local files accessible to the NiceGUI server process.
- CVE-2026-39844Medium
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.

