A memory-safety vulnerability in Open Babel's GAMESS output parser caused a use-after-free when reading a crafted input file.

The flaw was in GAMESSOutputFormat::ReadMolecule. A malformed input caused the parser to dereference a stale pointer after the underlying object had been freed.

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 GAMESS output file with the obabel tool, the OBConversion API, or any of the language bindings (Python, Ruby, Java, R, Perl, C#, PHP).

All releases up to and including 3.1.1.

3.2.0 (released 2026-05-26).

Fix commit: https://github.com/openbabel/openbabel/commit/95033d27 Originally reported as #2834; 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.

Reported via OSS-Fuzz.