{"id":"CVE-2026-116266","state":"PUBLISHED","title":"MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous","description":"MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous.\n\nThe multipart_boundary() method decodes RFC 2047 encoded words anywhere in the boundary, but the ambiguity check only fires when the whole value is one encoded word. A boundary such as abc=?us-ascii?Q?def?= is used as abcdef, and ambiguous_content() returns false.\n\nEncoded words are not allowed in parameters, so other mail readers split the message on the literal value. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.","publishedAt":"2026-10-28T17:32:28.565Z","updatedAt":"2026-10-28T17:32:28.565Z","severity":null,"assigner":"CPANSec","products":["MIME-tools"],"affected":[{"packageName":"MIME-tools","packageURL":"pkg:cpan/MIME-tools","defaultStatus":"unaffected","versions":[{"version":"5.518","status":"affected","lessThan":"5.521","versionType":"custom"}],"collectionURL":"https://cpan.org/modules","modules":["MIME::Head"],"programFiles":["lib/MIME/Head.pm","lib/MIME/Field/ParamVal.pm"],"programRoutines":[{"name":"MIME::Head::multipart_boundary"},{"name":"MIME::Field::ParamVal::parse_params"}],"repo":"https://salsa.debian.org/dskoll/mime-tools"}],"references":["https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes"],"weaknesses":["CWE-436"],"ingestedAt":"2026-10-29T20:10:43.281Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/116xxx/CVE-2026-116266.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-116266","state":"PUBLISHED","datePublished":"2026-10-28T17:32:28.565Z","dateUpdated":"2026-10-28T17:32:28.565Z","assignerShortName":"CPANSec","assignerOrgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateReserved":"2026-10-25T18:05:02.235Z"},"containers":{"cna":{"title":"MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous","descriptions":[{"lang":"en","value":"MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous.\n\nThe multipart_boundary() method decodes RFC 2047 encoded words anywhere in the boundary, but the ambiguity check only fires when the whole value is one encoded word. A boundary such as abc=?us-ascii?Q?def?= is used as abcdef, and ambiguous_content() returns false.\n\nEncoded words are not allowed in parameters, so other mail readers split the message on the literal value. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it."}],"affected":[{"packageName":"MIME-tools","packageURL":"pkg:cpan/MIME-tools","defaultStatus":"unaffected","versions":[{"version":"5.518","status":"affected","lessThan":"5.521","versionType":"custom"}],"collectionURL":"https://cpan.org/modules","modules":["MIME::Head"],"programFiles":["lib/MIME/Head.pm","lib/MIME/Field/ParamVal.pm"],"programRoutines":[{"name":"MIME::Head::multipart_boundary"},{"name":"MIME::Field::ParamVal::parse_params"}],"repo":"https://salsa.debian.org/dskoll/mime-tools"}],"references":[{"url":"https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes","tags":["release-notes"]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-436","description":"CWE-436 Interpretation Conflict","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"CPANSec","orgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateUpdated":"2026-10-28T17:32:28.565Z"},"solutions":[{"lang":"en","value":"Upgrade to MIME-tools 5.521 or later."}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"cpansec-cna-tool 0.1"}}}}}