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Maven
Not in CISA KEV
MEDIUM severity

CVE-2019-9658

MEDIUMFix: checkstyle/checkstyle#6476

CVE-2019-9658 is a medium-severity (CVSS 5.3) XML External Entity (XXE) vulnerability in com.puppycrawl.tools:checkstyle. O3 Security confirms whether CVE-2019-9658 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Moderate severity vulnerability that affects com.puppycrawl.tools:checkstyle

Also known asGHSA-gp32-7h29-rpxm
Published
Mar 11, 2019
Updated
Jul 8, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Jul 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
com.puppycrawl.tools:checkstyle

Real-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

Checkstyle before 8.18 loads external DTDs by default.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
Mavencom.puppycrawl.tools:checkstyleall versions8.18

Detection & mitigation playbook

Open-source dependency
  1. Detect

    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.

  2. Fix

    Update com.puppycrawl.tools:checkstyle to 8.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-9658 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 CVE-2019-9658 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 CVE-2019-9658. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Checkstyle before 8.18 loads external DTDs by default.
O3 Security · Impact-Aware SCA

Is CVE-2019-9658 in your dependencies?

O3 detects CVE-2019-9658 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

CVE-2019-9658: checkstyle (Medium 5.3) | O3 Security