CVE-2026-116271 Affecting libmime-tools-perl package, versions *

Note: Versions mentioned in the description apply only to the upstream libmime-tools-perl package and not the libmime-tools-perl package as distributed by Debian. See How to fix? for Debian:12 relevant fixed versions and status.

MIME::Parser::FileUnder versions before 5.521 for Perl reuse a pre-created output directory and follow symlinks in it, letting local users redirect attachment writes.

Each message is written to a directory named msg-<time>-<pid>-<n> under the output base, and an existing directory of that name is used as is. A file name counts as unused when nothing exists at that path, which holds for a dangling symlink, and the body file is then opened in a way that follows the link.

When the output base is writable by other users, as with output_under("/tmp"), a local user can pre-create the directory with a symlink named like an attachment. The parser then writes the attachment to the link target with the privileges of the parsing process.

• https://security-tracker.debian.org/tracker/CVE-2026-116271
• https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes