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GHSA-vfmq-68hx-4jfw

HIGH

GHSA-vfmq-68hx-4jfw is a high-severity (CVSS 7.5) vulnerability in lxml. O3 Security confirms whether GHSA-vfmq-68hx-4jfw is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

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

Also known asCVE-2026-41066PYSEC-2026-87
Published
Apr 21, 2026
Updated
Jun 6, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

Real-World Exposure

1 pkg affected
🐍lxml

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIlxmlall versions6.1.0

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lxml. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update lxml to 6.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vfmq-68hx-4jfw is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-vfmq-68hx-4jfw is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-vfmq-68hx-4jfw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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
O3 Security · Impact-Aware SCA

Is GHSA-vfmq-68hx-4jfw in your dependencies?

O3 detects GHSA-vfmq-68hx-4jfw across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.