GHSA-q43m-vhcp-mhvm: Path Traversal
Summary
When the HTML backend renders pages in a headless browser (HTMLBackendOptions(renderpage=True)), the enablelocalfetch option is not enforced. A crafted HTML file can embed an arbitrary local file (for example with <iframe src="file:///...">), and that file's contents appear in the page image attached to the returned DoclingDocument.
Details
In render mode, Playwright requests are filtered by HTMLDocumentBackend.getbrowserrequestblockreason. In affected versions, this check allowed file: URLs unconditionally, before reading any option. As a result:
- enablelocalfetch=False did not block local file access, and - even with enablelocalfetch=True, file access was not limited to the source document's directory, unlike the non-render path (ImageResourceLoader), which rejects absolute paths and path traversal.
Versions 2.82.0–2.90.x did no request filtering in render mode at all.
The browser runs with JavaScript disabled (from 2.91.0), so disclosure is passive: only what Chromium renders visibly inside the page viewport ends up in the page image.
Only Path inputs are affected. They are loaded through a file:// URL. Stream inputs are loaded with page.setcontent() into an opaque origin, from which Chromium does not load file:// subresources.
Impact
An attacker who can submit HTML for conversion can read any text file the conversion process can read (for example .env files, credential files, or other users' documents on a shared host) by having it rendered into the page image.
Only applications that meet all of these conditions are affected:
- they set HTMLBackendOptions(renderpage=True) in Python, - they have the optional playwright dependency installed, and - they pass untrusted HTML as a filesystem Path.
The following are not affected: the default configuration (renderpage=False), the docling CLI, docling-serve, and the EPUB, Markdown, XBRL and email backends.
Patches
Fixed in 2.118.1 (#3948). In render mode, file: requests are now blocked unless enablelocalfetch=True, and allowed requests are limited to the source document's directory.
Workarounds
If you can't upgrade, don't use renderpage=True on untrusted HTML, or pass the input as a stream instead of a Path.
Credits
Reported by @priyankn.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
pip/docling-slimto a version that resolves this vulnerability.Fixed in 2.118.1 - Upgrade
Upgrade
pip/doclingto a version that resolves this vulnerability.Fixed in 2.118.1 - Upgrade
Upgrade
doclingto a version that resolves this vulnerability.Fixed in 2.118.1Patch #3948 - Configuration
Do not use render_page=True when converting untrusted HTML.
HTML backend render_page = False - Compensating control
Pass untrusted HTML as a stream instead of a filesystem Path.
Event History
Frequently Asked Questions
Which processing workflows are exposed?
Only HTML processing that uses the HTML backend with render_page=True and supplies the document as a Path input is affected. Stream inputs are not affected because they are not loaded through a file:// URL.
What does an attacker need to exploit this issue?
An attacker needs to provide a crafted HTML file that the application processes in render mode. The file can reference local files using file: URLs, such as in an iframe, causing visibly rendered content to be included in the returned DoclingDocument page image.
Does setting enable_local_fetch=False prevent this exposure?
No. In the affected render path, file: URLs were allowed before the enable_local_fetch setting was evaluated, so enable_local_fetch=False did not block local file access.
How can I assess whether a deployment may be affected?
Check whether it processes untrusted HTML Path inputs with HTMLBackendOptions(render_page=True). Versions 2.82.0 through 2.90.x performed no request filtering in render mode; later behavior described here still allowed file: URLs without enforcing the local-fetch option or source-directory restriction.