Open Babel has Use-after-free in GAMESS GAMESSOutputFormat::ReadMolecule

Summary

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

Details

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

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 GAMESS output 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/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.

Credit

Reported via OSS-Fuzz.