CVE-2024-32021

Git is a revision control system. Prior to versions 2.45.1, 2.44.1, 2.43.4,
2.42.2, 2.41.1, 2.40.2, and 2.39.4, when cloning a local source repository
that contains symlinks via the filesystem, Git may create hardlinks to
arbitrary user-readable files on the same filesystem as the target
repository in the objects/ directory. Cloning a local repository over the
filesystem may creating hardlinks to arbitrary user-owned files on the same
filesystem in the target Git repository’s objects/ directory. When
cloning a repository over the filesystem (without explicitly specifying the
file:// protocol or --no-local), the optimizations for local cloning
will be used, which include attempting to hard link the object files
instead of copying them. While the code includes checks against symbolic
links in the source repository, which were added during the fix for
CVE-2022-39253, these checks can still be raced because the hard link
operation ultimately follows symlinks. If the object on the filesystem
appears as a file during the check, and then a symlink during the
operation, this will allow the adversary to bypass the check and create
hardlinks in the destination objects directory to arbitrary, user-readable
files. The problem has been patched in versions 2.45.1, 2.44.1, 2.43.4,
2.42.2, 2.41.1, 2.40.2, and 2.39.4.

Bugs

• <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1071160&gt;