Summary
When the HTML backend renders pages in a headless browser (HTMLBackendOptions(render_page=True)), the enable_local_fetch 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._get_browser_request_block_reason. In affected versions, this check allowed file: URLs unconditionally, before reading any option. As a result:
enable_local_fetch=False did not block local file access, and- even with
enable_local_fetch=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.set_content() 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(render_page=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 (render_page=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 enable_local_fetch=True, and allowed requests are limited to the source document's directory.
Workarounds
If you can't upgrade, don't use render_page=True on untrusted HTML, or pass the input as a stream instead of a Path.
Credits
Reported by @priyankn.
References
priyankn Reporter
DavidCarliez Reporter
Summary
When the HTML backend renders pages in a headless browser (
HTMLBackendOptions(render_page=True)), theenable_local_fetchoption 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 returnedDoclingDocument.Details
In render mode, Playwright requests are filtered by
HTMLDocumentBackend._get_browser_request_block_reason. In affected versions, this check allowedfile:URLs unconditionally, before reading any option. As a result:enable_local_fetch=Falsedid not block local file access, andenable_local_fetch=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
Pathinputs are affected. They are loaded through afile://URL. Stream inputs are loaded withpage.set_content()into an opaque origin, from which Chromium does not loadfile://subresources.Impact
An attacker who can submit HTML for conversion can read any text file the conversion process can read (for example
.envfiles, 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:
HTMLBackendOptions(render_page=True)in Python,playwrightdependency installed, andPath.The following are not affected: the default configuration (
render_page=False), thedoclingCLI,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 unlessenable_local_fetch=True, and allowed requests are limited to the source document's directory.Workarounds
If you can't upgrade, don't use
render_page=Trueon untrusted HTML, or pass the input as a stream instead of aPath.Credits
Reported by @priyankn.
References