A vulnerability was detected in Open Babel up to 3.1.1. This issue affects the function OBSmilesParser::ParseSmiles of the file /src/formats/smilesformat.cpp. Performing manipulation results in heap-based buffer overflow. The attack needs to be approached locally. The exploit is now public and may be used.

Affected: PyPI: openbabel

### Summary

A memory-safety vulnerability in Open Babel's SMILES parser caused a heap buffer overflow when reading a crafted input string.

### Details

The flaw was in `OBSmilesParser::ParseSmiles`. A malformed SMILES input caused the parser to write past the end of a heap-allocated buffer.

### 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 parse a malicious SMILES string with the `obabel` tool, the `OBConversion` API, or any of the language bindings (Python, Ruby, Java, R, Perl, C#, PHP). SMILES strings are commonly passed on the command line and through scripted pipelines, so this primitive is especially reachable.

### 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/b34cd604 Originally reported as #2831; 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.

libopenbabel8-3.2.0-1.1 on GA media

Affected: PyPI: openbabel

### Summary

A memory-safety vulnerability in Open Babel's SMILES parser caused a heap buffer overflow when reading a crafted input string.

### Details

The flaw was in `OBSmilesParser::ParseSmiles`. A malformed SMILES input caused the parser to write past the end of a heap-allocated buffer.

### 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 parse a malicious SMILES string with the `obabel` tool, the `OBConversion` API, or any of the language bindings (Python, Ruby, Java, R, Perl, C#, PHP). SMILES strings are commonly passed on the command line and through scripted pipelines, so this primitive is especially reachable.

### 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/b34cd604 Originally reported as #2831; 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 vulnerability was detected in Open Babel up to 3.1.1. This issue affects the function OBSmilesParser::ParseSmiles of the file /src/formats/smilesformat.cpp. Performing manipulation results in heap-based buffer overflow. The attack needs to be approached locally. The exploit is now public and may be used.