PYSEC-2026-2680 NiceGUI: Unauthenticated log-volume denial of service in dynamic resource routes

Summary 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...

PYSEC-2026-2679 NiceGUI: Local file disclosure via Docutils file insertion in ui.restructured_text()

Summary ui.restructuredtext renders reStructuredText server-side with Docutils without disabling file insertion directives. When a NiceGUI application passes attacker-controlled content to ui.restructuredtext, an attacker can use standard Docutils directives include, csv-table with :file:, raw wi...

PYSEC-2026-1703 NiceGUI has Redis connection leak via tab storage causes service degradation

Summary An unauthenticated attacker can exhaust Redis connections by repeatedly opening and closing browser tabs on any NiceGUI application using Redis-backed storage. Connections are never released, leading to service degradation when Redis hits its connection limit. NiceGUI continues accepting...

PYSEC-2026-1701 NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-provided links

Summary An unsafe implementation in the click event listener used by ui.subpages, combined with attacker-controlled link rendering on the page, causes an XSS when the user actively clicks on the link. Details 1. On click, eventually subpagesnavigate event is emitted...

PYSEC-2026-1698 NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace()

Summary XSS risk exists in NiceGUI when developers pass attacker-controlled strings into ui.navigate.history.push or ui.navigate.history.replace. These helpers are documented as History API wrappers for updating the browser URL without page reload. However, if the URL argument is embedded into...

PYSEC-2026-1702 NiceGUI apps which use `ui.sub_pages` vulnerable to zero-click XSS

Summary An unsafe implementation in the pushstate event listener used by ui.subpages allows an attacker to manipulate the fragment identifier of the URL, which they can do despite being cross-site, using an iframe. Details The problem is traced as follows: 1. On pushstate, handleStateEvent is...

PYSEC-2026-1697 NiceGUI Reflected XSS in ui.add_css, ui.add_scss, and ui.add_sass via Style Injection

Summary A Cross-Site Scripting XSS vulnerability exists in ui.addcss, ui.addscss, and ui.addsass functions in NiceGUI v3.3.1 and earlier. These functions allow developers to inject styles dynamically. However, they lack proper sanitization or encoding for the JavaScript context they generate. An...

PYSEC-2026-1700 NiceGUI has a path traversal in app.add_media_files() allows arbitrary file read

Summary A directory traversal vulnerability in NiceGUI's App.addmediafiles allows a remote attacker to read arbitrary files on the server filesystem. Details Hello, I am Seungbin Yang, a university student studying cybersecurity. While reviewing the source code of the repository, I discovered a...

PYSEC-2026-1696 NiceGUI Stored/Reflected XSS in ui.interactive_image via unsanitized SVG content

Summary A Cross-Site Scripting XSS vulnerability exists in the ui.interactiveimage component of NiceGUI v3.3.1 and earlier. The component renders SVG content using Vue's v-html directive without any sanitization. This allows attackers to inject malicious HTML or JavaScript via the SVG tag. Detail...

PYSEC-2026-1699 NiceGUI has a Reflected XSS

Summary A Cross-Site Scripting XSS risk exists in NiceGUI when developers render unescaped user input into the DOM using ui.html. Before version 3.0, NiceGUI does not enforce HTML or JavaScript sanitization, so applications that directly combine components like ui.input with ui.html without...

PYSEC-2026-1705 NiceGUI On Air authentication issue

Summary Once a user logins to one browser, all other browsers are logged in without entering password. Even incognito mode. Impact high...

PYSEC-2026-1704 NiceGUI allows potential access to local file system

NiceGUI is an easy-to-use, Python-based UI framework. A local file inclusion is present in the NiceUI leaflet component when requesting resource files under the /nicegui/version/resources/key/path:path route. As a result any file on the backend filesystem which the web server has access to can be...

CVE-2026-45554

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...

CVE-2026-39844

NiceGUI is a Python-based UI framework. Prior to 3.10.0, Since PurePosixPath only recognizes forward slashes / as path separators, an attacker can bypass this sanitization on Windows by using backslashes \ in the upload filename. Applications that construct file paths using file.name a pattern...

CVE-2026-45553

NiceGUI is a Python-based UI framework. Prior to version 3.12.0, ui.restructuredtext renders reStructuredText server-side with Docutils without disabling file insertion directives. When a NiceGUI application passes attacker-controlled content to ui.restructuredtext, an attacker can use standard...

CVE-2026-45553

NiceGUI is a Python-based UI framework. Prior to version 3.12.0, ui.restructuredtext renders reStructuredText server-side with Docutils without disabling file insertion directives. When a NiceGUI application passes attacker-controlled content to ui.restructuredtext, an attacker can use standard...

CVE-2026-45554

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...

EUVD-2026-33965

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...

CVE-2026-45554 NiceGUI: Unauthenticated log-flood DoS via trailing slash on ESM and per-component resource routes

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...

CVE-2026-45554

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...