GitHub Advisoryadvisory · PyPI

GHSA-vfmq-68hx-4jfw lxml: Default configuration of iterparse() and ETCompatXMLParser() allows XXE to local files

HIGH Published 2026-04-21 Modified 2026-06-06 Official page ↗
Aliases
CVE-2026-41066
Ecosystem
PyPI
Packages
lxml
Severity
High
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weaknesses
CWE-611
Reviewed
2026-04-21

Affected packages

• PyPI lxml: < 6.1.0 → fixed in 6.1.0

Description

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.

Related

Alias · CVE (1)

  • CVE-2026-41066 lxml is a library for processing XML and HTML in the Python language. vulnerability

Weakness · CWE (1)

  • CWE-611 Improper Restriction of XML External Entity Reference weakness

References