MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary. Parameter parsing stops at the first parameter whose name it cannot read, such as x:y=1 or a name containing an 8-bit byte, and drops every parameter after it. When the boundary is among them, MIME::Parser keeps the multipart body as a single undecoded part without marking the parse as ambiguous. Mail readers that skip the invalid parameter still find the boundary. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.
History

Fri, 06 Nov 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 30 Oct 2026 12:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-1286
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}

threat_severity

Moderate


Wed, 28 Oct 2026 22:30:00 +0000

Type Values Removed Values Added
First Time appeared Perl
Perl mime::field::paramval
Vendors & Products Perl
Perl mime::field::paramval

Wed, 28 Oct 2026 17:45:00 +0000

Type Values Removed Values Added
Description MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary. Parameter parsing stops at the first parameter whose name it cannot read, such as x:y=1 or a name containing an 8-bit byte, and drops every parameter after it. When the boundary is among them, MIME::Parser keeps the multipart body as a single undecoded part without marking the parse as ambiguous. Mail readers that skip the invalid parameter still find the boundary. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.
Title MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary
Weaknesses CWE-436
References

cve-icon MITRE

Status: PUBLISHED

Assigner: CPANSec

Published: 2026-10-28T17:31:52.187Z

Updated: 2026-11-05T21:05:49.448Z

Reserved: 2026-10-25T18:05:02.235Z

Link: CVE-2026-116264

cve-icon Vulnrichment

Updated: 2026-11-05T21:05:29.349Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-28T18:17:12.797

Modified: 2026-11-05T21:18:37.670

Link: CVE-2026-116264

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-28T17:31:52Z

Links: CVE-2026-116264 - Bugzilla