CVE-2026-45554
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedNiceGUI 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceNiceGUI versions before 3.12.0 have two FastAPI routes for serving per-component static assets that accept a sub-path parameter. When this parameter resolves to a directory instead of a file, Starlette's FileResponse raises an unhandled RuntimeError. Since these routes are accessible without authentication, remote attackers can repeatedly trigger this error to cause log amplification and consume disk/log-pipeline capacity.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed NiceGUI versionRun `pip show nicegui` or check your dependency lock file for the nicegui package versionAffected if Version is lower than 3.12.0
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Verify the application uses NiceGUI's built-in static asset servingInspect your application startup code to confirm you are using NiceGUI's default run() method or ui.run() which registers the vulnerable static asset routesAffected if Your application uses NiceGUI's default static asset serving without custom routing that blocks the vulnerable endpoints
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Confirm the static asset routes are network-accessibleCheck your server's bind address and firewall rules to determine if the NiceGUI application port (default 8080) is exposed to unauthenticated network accessAffected if The NiceGUI server port is reachable from untrusted networks without authentication barriers
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Look for the characteristic error signature in server logsSearch your Uvicorn/server logs for entries containing 'RuntimeError' and 'Is a directory' or similar path-resolution failures related to static asset requestsAffected if Your logs contain repeated RuntimeError tracebacks indicating directory path traversal attempts on static asset routes
You are affected if NiceGUI version is below 3.12.0 AND the application serves static assets via the default NiceGUI routes on an accessible port, as evidenced by unauthenticated requests triggering RuntimeError tracebacks in logs.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade NiceGUI to version 3.12.0 or later, which contains the patch for this vulnerability. Consider implementing log rotation or rate limiting as a defense-in-depth measure.
NiceGUI 3.12.0
- Check the currently installed NiceGUI version using `pip show nicegui` or `pip list | grep nicegui`
- Upgrade NiceGUI to version 3.12.0 or later using `pip install --upgrade nicegui>=3.12.0`
- Verify the upgrade was successful by checking the installed version with `pip show nicegui`
- Restart the NiceGUI application to ensure the patched version is loaded
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-45554 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-45554 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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