GHSA-55j6-rjhx-hwfh is a medium-severity (CVSS 5.5) CWE-404 vulnerability in openbabel. O3 Security confirms whether GHSA-55j6-rjhx-hwfh is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Open Babel has NULL pointer dereference in CACAO CacaoFormat::SetHilderbrandt
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-55j6-rjhx-hwfh.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-55j6-rjhx-hwfh plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 369,023 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
openbabelReal-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
Summary
A memory-safety vulnerability in Open Babel's CACAO parser caused a NULL pointer dereference when reading a crafted input file.
Details
The flaw was in CacaoFormat::SetHilderbrandt. A malformed input
caused the parser to dereference a NULL pointer while applying the
Hilderbrandt transformation.
Impact
Open Babel is a C++ library and CLI used to read and write chemistry
file formats; it is shipped by Linux distributions and embedded in
services that may parse untrusted input. Triggering this vulnerability
requires the victim to open a malicious CACAO file with the obabel
tool, the OBConversion API, or any of the language bindings (Python,
Ruby, Java, R, Perl, C#, PHP).
Affected versions
All releases up to and including 3.1.1.
Patched version
3.2.0 (released 2026-05-26).
Patch
Fix commit: https://github.com/openbabel/openbabel/commit/ecaed96f Originally reported as #2827; fixes consolidated in #2913.
A minimized reproducer for this CVE is checked in under
test/files/fuzz_regress/ and is exercised on every CI build under
ASAN+UBSAN by the fuzzregresstest harness.
Credit
Reported via OSS-Fuzz.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | openbabel | all versions | 3.2.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openbabel. 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 openbabel to 3.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-55j6-rjhx-hwfh 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-55j6-rjhx-hwfh 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-55j6-rjhx-hwfh. 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-55j6-rjhx-hwfh in your dependencies?
O3 detects GHSA-55j6-rjhx-hwfh across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.