CVE-2026-116264

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.

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Weakness Type (CWE)

CWE-436 CWE-436

References

Other References

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

Frequently Asked Questions

What is CVE-2026-116264? +

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.

How do I check if I'm vulnerable to CVE-2026-116264? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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