CVE-2026-64613

Data::Buffer::Shared versions before 0.05 for Perl create a world-readable mmap backing file and open it without O NOFOLLOW.

The segment is created in buf generic.h with open(path, O RDWR|O CREAT|O EXCL, 0666). O EXCL blocks a pre-seeded file on create, but the mode is 0666, so under the default umask 022 the file is created mode 0644 (world-readable), and O NOFOLLOW is absent, so a symlink planted at the path is followed when the segment is attached.

A "Shared" segment naturally lives in a shared directory such as /tmp or /dev/shm, where any local user can read the IPC payloads stored in the world-readable segment, and a pre-planted symlink at the path redirects the open to another file.