A weakness has been identified in Open Babel up to 3.1.1. This affects the function GAMESSOutputFormat::ReadMolecule of the file gamessformat.cpp. This manipulation causes use after free. It is possible to launch the attack on the local host. The exploit has been made available to the public and could be exploited.

Affected: PyPI: openbabel

### 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.

libopenbabel8-3.2.1-1.1 on GA media

Affected: PyPI: openbabel

### 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.

Affected: Ubuntu:16.04:LTS: openbabel, Ubuntu:18.04:LTS: openbabel, Ubuntu:20.04:LTS: openbabel, Ubuntu:22.04:LTS: openbabel, Ubuntu:24.04:LTS: openbabel, Ubuntu:25.10: openbabel, Ubuntu:26.04:LTS: openbabel

A weakness has been identified in Open Babel up to 3.1.1. This affects the function GAMESSOutputFormat::ReadMolecule of the file gamessformat.cpp. This manipulation causes use after free. It is possible to launch the attack on the local host. The exploit has been made available to the public and could be exploited.