libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, git delta apply in src/libgit2/delta.c trusts the attacker-controlled res sz value parsed by hdr sz from a delta object header and passes that amount to git malloc before validating delta instructions. Malicious pack data supplied through git clone, git fetch, git remote fetch, git indexer append, or a local attacker-supplied repository can use a very small multi-level OFS DELTA chain to retain extremely large allocations and exhaust memory. This issue is fixed in versions 1.8.6 and 1.9.5.