GHSA-rxpr-wq63-jr7p Open Babel has a NULL pointer dereference in CDXML OBAtom::GetExplicitValence

• PyPI openbabel: < 3.2.0 → fixed in 3.2.0

Summary A memory-safety vulnerability in Open Babel's CDXML file format parser caused a NULL pointer dereference when reading a crafted input file. Details The flaw was in `OBAtom::GetExplicitValence` as called from the CDXML parser. A malformed fragment caused the parser to invoke the method on a NULL atom pointer. 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 CDXML 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/e23a224b Tracked in #2862. 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 by Vedant Madane (@VedantMadane) via VulDB.