CVE-2026-41066: lxml: Default configuration of iterparse() and ETCompatXMLParser() allows XXE to local files

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-24 · updated 2026-06-17
Weakness: CWE-611

Description

lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.0, using either of the two parsers in the default configuration (with resolve_entities=True) allows untrusted XML input to read local files. Setting the resolve_entities option explicitly to resolve_entities='internal' or resolve_entities=False disables the local file access. This vulnerability is fixed in 6.1.0.

Affected products

lxml: before 6.1.0 — fixed in 6.1.0
Pypi Lxml: before 6.1.0; 1.3.2, 1.3.3, 1.3.4, 1.3.5, 1.3.6, 2.0 (+116) — fixed in 6.1.0

How to fix

Upgrade to a fixed version: lxml 6.1.0; Pypi Lxml 6.1.0. Check the vendor advisory for mitigations.

References

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