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MEDIUM5.5

PYSEC-2026-2772

Open Babel has NULL pointer dereference in CACAO CacaoFormat::SetHilderbrandt

Quick fix

PYSEC-2026-2772 — openbabel: upgrade to the fixed version with the command below.

pip install --upgrade 'openbabel>=3.2.0'

Details

### 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.

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/openbabel
Introduced in: 0Fixed in: 3.2.0
Fixpip install --upgrade 'openbabel>=3.2.0'

References