CVE-2026-116264: medium-severity vulnerability in MIME-tools
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
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.2%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Affected products
MIME-toolsRelated CVEs — MIME-tools
In the same product, most dangerous first.
CVE-2026-116271HIGHMIME::Parser::FileUnder versions before 5.521 for Perl reuse a pre-created output directory and follow symlinks in it, letting local users redirect attachment writesEPSS 0.2%CVE-2026-116273HIGHMIME::Parser versions before 5.521 for Perl set no limit on the number of message parts by default, allowing memory exhaustionEPSS 0.2%CVE-2026-116272MEDIUMMIME::Field::ParamVal versions before 5.521 for Perl do not flag a duplicate boundary parameter whose name contains a nested commentEPSS 0.2%CVE-2026-116270HIGHMIME::Words versions before 5.521 for Perl allow memory exhaustion via repeated "=?" sequences in decode_mimewordsEPSS 0.2%CVE-2026-116269MEDIUMMIME::Field::ParamVal versions before 5.521 for Perl turn an RFC 2231 filename with a hyphenated language tag into an empty recommended filenameEPSS 0.2%CVE-2026-116268HIGHMIME::Field::ParamVal versions before 5.521 for Perl allow CPU exhaustion via unclosed comments in header parametersEPSS 0.2%