GHSA-763g-fqq7-48wg is a medium-severity (CVSS 5.3) XML External Entity (XXE) vulnerability in com.puppycrawl.tools:checkstyle. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-763g-fqq7-48wg is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
XML external entity (XXE) processing ('external-parameter-entities' feature was not fully disabled))
Real-World Exposure
com.puppycrawl.tools:checkstyleReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Due to an incomplete fix for CVE-2019-9658, checkstyle was still vulnerable to XML External Entity (XXE) Processing.
Impact
User: Build Maintainers
This vulnerability probably doesn't impact Maven/Gradle users as, in most cases, these builds are processing files that are trusted, or pre-vetted by a pull request reviewer before being run on internal CI infrastructure.
User: Static Analysis as a Service
If you operate a site/service that parses "untrusted" Checkstyle XML configuration files, you are vulnerable to this and should patch.
Note from the discoverer of the original CVE-2019-9658:
While looking at a few companies that run Checkstyle/PMD/ect... as a service I notice that it's a common pattern to run the static code analysis tool inside of a Docker container with the following flags:
--net=none \ --privileged=false \ --cap-drop=ALLRunning the analysis in Docker has the advantage that there should be no sensitive local file information that XXE can exfiltrate from the container. Additionally, these flags prevent vulnerabilities in static analysis tools like Checkstyle from being used to exfiltrate data via XXE or to perform SSRF. - Jonathan Leitschuh
Patches
Has the problem been patched? What versions should users upgrade to?
Patched, will be released with version 8.29 at 26 Jan 2020.
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
No workaround are available
References
- CWE-611: Improper Restriction of XML External Entity Reference
- GitHub Issue https://github.com/checkstyle/checkstyle/issues/7468
For more information
If you have any questions or comments about this advisory:
- Open an issue in https://github.com/checkstyle/checkstyle/issues
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.puppycrawl.tools:checkstyle | all versions | 8.29 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.puppycrawl.tools:checkstyle. 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.
Fix
Update com.puppycrawl.tools:checkstyle to 8.29 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-763g-fqq7-48wg is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-763g-fqq7-48wg 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-763g-fqq7-48wg. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-763g-fqq7-48wg in your dependencies?
O3 detects GHSA-763g-fqq7-48wg across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.