NiceGUI: Local file disclosure via Docutils file insertion in ui.restructured_text()GHSA-jfrm-rx66-g536
HIGHGHSA-jfrm-rx66-g536 is a high-severity (CVSS 7.5) Information Exposure vulnerability in nicegui. A fix is available for nicegui — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-jfrm-rx66-g536.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
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
ui.restructured_text() renders reStructuredText server-side with Docutils without disabling file insertion directives.
When a NiceGUI application passes attacker-controlled content to ui.restructured_text(), an attacker can use standard Docutils directives (include, csv-table with :file:, raw with :file:) to read local files readable by the NiceGUI server process.
Applications that only pass trusted static strings to ui.restructured_text() are not affected.
Details
The affected component is the reStructuredText renderer:
- File:
nicegui/elements/restructured_text.py - Function:
prepare_content()
prepare_content() renders user-supplied reStructuredText through Docutils:
html = publish_parts(
remove_indentation(content),
writer_name='html4',
settings_overrides={'syntax_highlight': 'short'},
)
The Docutils call only sets syntax_highlight. It does not disable file insertion or raw directives, so Docutils processes directives that read local files and embed their contents into the generated HTML before it is returned to the browser. Frontend sanitization cannot prevent this because the file has already been read server-side.
A minimal vulnerable usage pattern is any page that forwards untrusted input into ui.restructured_text(), e.g. content taken from query parameters, form fields, or other user-controlled sources.
Impact
Local file disclosure. An attacker who can supply reStructuredText content can read files accessible to the NiceGUI server process. Depending on deployment, this may expose:
- application
.envfiles - database URLs, API tokens, session/storage secrets
- OAuth or cloud credentials
- Docker or Kubernetes mounted secrets
- application source files
- logs and other process-readable files
The confirmed impact is confidentiality loss through arbitrary local file read. Applications are only impacted when they pass untrusted or user-controlled reStructuredText into ui.restructured_text().
Recommended fix
Disable unsafe Docutils features in prepare_content():
html = publish_parts(
remove_indentation(content),
writer_name='html4',
settings_overrides={
'syntax_highlight': 'short',
'file_insertion_enabled': False,
'raw_enabled': False,
'_disable_config': True,
},
)
This blocks the include, csv-table :file:, and raw :file: directives as well as local docutils.conf overrides.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | nicegui | all versions | 3.12.0pip install --upgrade 'nicegui==3.12.0' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nicegui, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update nicegui to 3.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jfrm-rx66-g536 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Frequently Asked Questions
Is GHSA-jfrm-rx66-g536 in your dependencies?
Find it across PyPI, including transitive dependencies.