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CVE-2026-116269                                      CPAN Security Group
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         CVE ID:  CVE-2026-116269

   Distribution:  MIME-tools
       Versions:  before 5.521
       MetaCPAN:  https://metacpan.org/dist/MIME-tools
       VCS Repo:  https://salsa.debian.org/dskoll/mime-tools

MIME::Field::ParamVal versions before 5.521 for Perl turn an RFC 2231
filename with a hyphenated language tag into an empty recommended
filename

Description
-----------
MIME::Field::ParamVal versions before 5.521 for Perl turn an RFC 2231
filename with a hyphenated language tag into an empty recommended
filename.

A parameter such as filename*=utf-8'en-US'payload.exe is converted to
an encoded word with the language tag appended to the charset. The
decoder strips the language suffix only when it is a single word, so it
cannot resolve the charset UTF-8*EN-US and returns an empty string. The
recommended_filename() method returns that empty string rather than
falling back to the name parameter.

Other mail readers return payload.exe. A remote sender can get an
attachment past a policy that checks file extensions on the recommended
filename.

Problem types
-------------
- CWE-436 Interpretation Conflict

Solutions
---------
Upgrade to MIME-tools 5.521 or later.

References
----------
https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes