{"id":"CVE-2026-63435","state":"PUBLISHED","title":"Mail: Email address spoofing via malformed RFC 2047 encoded-words","description":"Mail is an internet library for Ruby designed to handle email generation, parsing, and sending. Prior to 2.9.1, Mail::Utilities.q_value_decode and Mail::Utilities.b_value_decode used a single String#match and an overly greedy charset capture to decode only the first RFC 2047 encoded-word and mishandle surrounding or subsequent text. A crafted malformed encoded-word in an address display name or local part could cross ? delimiters and make decoded From, To, or Reply-To header values differ from the raw values inspected by a human reviewer or downstream parser, enabling apparent sender or recipient spoofing, phishing, or authorization-check bypass. This issue is fixed in version 2.9.1.","publishedAt":"2026-09-01T20:09:20.820Z","updatedAt":"2026-09-02T15:44:56.368Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["mikel mail"],"affected":[{"vendor":"mikel","product":"mail","versions":[{"version":"< 2.9.1","status":"affected"}]}],"references":["https://github.com/mikel/mail/security/advisories/GHSA-mvxr-6m87-mv2q","https://github.com/mikel/mail/pull/1664","https://github.com/mikel/mail/commit/f9d59c2e447af42e2c3dec5a56b1bb25c7292859","https://github.com/mikel/mail/releases/tag/2.9.1"],"weaknesses":["CWE-436"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63435.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63435","state":"PUBLISHED","datePublished":"2026-09-01T20:09:20.820Z","dateUpdated":"2026-09-02T15:44:56.368Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-16T19:35:57.767Z"},"containers":{"cna":{"title":"Mail: Email address spoofing via malformed RFC 2047 encoded-words","descriptions":[{"lang":"en","value":"Mail is an internet library for Ruby designed to handle email generation, parsing, and sending. Prior to 2.9.1, Mail::Utilities.q_value_decode and Mail::Utilities.b_value_decode used a single String#match and an overly greedy charset capture to decode only the first RFC 2047 encoded-word and mishandle surrounding or subsequent text. A crafted malformed encoded-word in an address display name or local part could cross ? delimiters and make decoded From, To, or Reply-To header values differ from the raw values inspected by a human reviewer or downstream parser, enabling apparent sender or recipient spoofing, phishing, or authorization-check bypass. This issue is fixed in version 2.9.1."}],"affected":[{"vendor":"mikel","product":"mail","versions":[{"version":"< 2.9.1","status":"affected"}]}],"references":[{"url":"https://github.com/mikel/mail/security/advisories/GHSA-mvxr-6m87-mv2q","name":"https://github.com/mikel/mail/security/advisories/GHSA-mvxr-6m87-mv2q","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/mikel/mail/pull/1664","name":"https://github.com/mikel/mail/pull/1664","tags":["x_refsource_MISC"]},{"url":"https://github.com/mikel/mail/commit/f9d59c2e447af42e2c3dec5a56b1bb25c7292859","name":"https://github.com/mikel/mail/commit/f9d59c2e447af42e2c3dec5a56b1bb25c7292859","tags":["x_refsource_MISC"]},{"url":"https://github.com/mikel/mail/releases/tag/2.9.1","name":"https://github.com/mikel/mail/releases/tag/2.9.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-436","lang":"en","description":"CWE-436: Interpretation Conflict","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-01T20:09:20.820Z"},"source":{"advisory":"GHSA-mvxr-6m87-mv2q","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-02T15:44:44.094469Z","id":"CVE-2026-63435","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-02T15:44:56.368Z"}}]}}}