GHSA-w5g8-5849-vj76
MEDIUMNiceGUI's unvalidated chunk size parameter in media routes can cause memory exhaustion
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
niceguiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
NiceGUI's app.add_media_file() and app.add_media_files() media routes accept a user-controlled query parameter that influences how files are read during streaming. The parameter is passed to the range-response implementation without validation, allowing an attacker to bypass chunked streaming and force the server to load entire files into memory at once.
With large media files and concurrent requests, this can lead to excessive memory consumption, degraded performance, or denial of service.
Impact
Affected applications: NiceGUI applications that serve media content via app.add_media_file() or app.add_media_files(), particularly those serving large files (video, audio).
What an attacker can do:
- Force the server to load entire files into memory instead of streaming them in chunks
- Amplify memory usage with concurrent requests to large media files
- Cause performance degradation, memory pressure, and potential OOM conditions
Attack difficulty: Low - requires only a crafted query parameter.
Remediation
Upgrade to a patched version of NiceGUI.
As a workaround, restrict access to media endpoints or strip unexpected query parameters at a reverse proxy layer.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | nicegui | all versions | 3.9.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nicegui. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update nicegui to 3.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w5g8-5849-vj76 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-w5g8-5849-vj76 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-w5g8-5849-vj76. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-w5g8-5849-vj76 in your dependencies?
O3 detects GHSA-w5g8-5849-vj76 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.