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GHSA-vfmq-68hx-4jfw

lxml: Default configuration of iterparse() and ETCompatXMLParser() allows XXE to local files

Source: GitHub Advisory Database (reviewed) High CVE-2026-41066

Packages

EcosystemPackageAffectedFixed in
PyPI lxml < 6.1.0 6.1.0

Details

As written in the advisory (Markdown source, shown as plain text).

### Impact Using either of the two parsers in the default configuration (with `resolve_entities=True`) allows untrusted XML input to read local files. ### Patches lxml 6.1.0 changes the default to `resolve_entities='internal'`, thus disallowing local file access by default. ### Workarounds Setting the `resolve_entities` option explicitly to `resolve_entities='internal'` or `resolve_entities=False` disables the local file access. ### Resources Original report: https://bugs.launchpad.net/lxml/+bug/2146291 The default option was changed to `resolve_entities='internal'` for the normal XML and HTML parsers in lxml 5.0. The default was not changed for `iterparse()` and `ETCompatXMLParser()` at the time. lxml 6.1 makes the safe option the default for all parsers.

References

External links from the advisory. They lead to third-party sites.