libgit2 is vulnerable to arbitrary code execution due to heap corruption in `git_index_add`
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. Using well-crafted inputs to `git_index_add` can cause heap corruption that could be leveraged for arbitrary code execution. There is an issue in the `has_dir_name` function in `src/libgit2/index.c`, which frees an entry that should not be freed. The freed entry is later used and overwritten with potentially bad actor-controlled data leading to controlled heap corruption. Depending on the application that uses libgit2, this could lead to arbitrary code execution. This issue
libgit2 is a cross-platform, linkable library implementation of Git. When using an SSH remote with the optional libssh2 backend, libgit2 does not perform certificate checking by default. Prior versions of libgit2 require the caller to set the `certificate_check` field of libgit2's `git_remote_callbacks` structure - if a certificate check callback is not set, libgit2 does not perform any certificate checking. This means that by default - without configuring a certificate check callback, clients will not perform validation on the server SSH keys and may be subject to a man-in-the-middle attack. Users are encouraged to upgrade to v1.4.5 or v1.5.