Git Security Measures and Reference Hiding

object. In addition, various other issues are checked for, including legacy issues (see `fsck.<msg-id>`), and potential security issues like the existence of a `.GIT` directory or a malicious `.gitmodules` file (see the release notes for v2.2.1 and v2.17.1 for details). Other sanity and security checks may be added in future releases. + On the receiving side, failing fsckObjects will make those objects unreachable, see "QUARANTINE ENVIRONMENT" in linkgit:git-receive-pack[1]. On the fetch side, malformed objects will instead be left unreferenced in the repository. + Due to the non-quarantine nature of the `fetch.fsckObjects` implementation it cannot be relied upon to leave the object store clean like `receive.fsckObjects` can. + As objects are unpacked they're written to the object store, so there can be cases where malicious objects get introduced even though the "fetch" failed, only to have a subsequent "fetch" succeed because only new incoming objects are checked, not those that have already been written to the object store. That difference in behavior should not be relied upon. In the future, such objects may be quarantined for "fetch" as well. + For now, the paranoid need to find some way to emulate the quarantine environment if they'd like the same protection as "push". E.g. in the case of an internal mirror do the mirroring in two steps, one to fetch the untrusted objects, and then do a second "push" (which will use the quarantine) to another internal repo, and have internal clients consume this pushed-to repository, or embargo internal fetches and only allow them once a full "fsck" has run (and no new fetches have happened in the meantime). transfer.hideRefs:: String(s) `receive-pack` and `upload-pack` use to decide which refs to omit from their initial advertisements. Use more than one definition to specify multiple prefix strings. A ref that is under the hierarchies listed in the value of this variable is excluded, and is hidden when responding to `git push` or `git fetch`. See `receive.hideRefs` and `uploadpack.hideRefs`

Git's `fsckObjects` option checks for malformed objects and security issues, while `hideRefs` allows hiding specific references from initial advertisements, enhancing security and access control in Git repositories.