Description
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.
References1
Metrics
- CVSS 3.1
-
7.0
HIGH
Score source: CNA
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 3 · as of 7 November 2026
- CWE
- CWE-59
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