---
id: CVE-2026-116269
title: >-
  MIME::Field::ParamVal versions before 5.521 for Perl turn an RFC 2231 filename
  with a hyphenated language tag into an empty recommended filename
summary: >-
  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…
severity: none
cwe:
  - CWE-436
product: MIME-tools
affected:
  - MIME-tools < 5.521
published: '2026-10-28'
updated: '2026-10-28'
sourceUpdated: '2026-10-28T17:33:22.332Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-116269'
references:
  - url: 'https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes'
tags:
  - cve.org
ingestedAt: '2026-10-28T18:15:46.382Z'
---

## Overview

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.

## Affected

- `MIME-tools < 5.521`

## Remediation

Upgrade to MIME-tools 5.521 or later.