{"id":"CVE-2026-67447","aliases":["GHSA-r553-m4fv-5v97"],"url":"https://o3.security/vulnerability/CVE-2026-67447","summary":"Mailpit: SMTP DATA line reader buffers over-limit input before size enforcement","details":"Mailpit is an email testing tool and API for developers. From 1.30.0 until 1.30.5, Mailpit's internal/smtpd/smtpd.go readData() function calls bufio.Reader.ReadBytes before applying the len(data)+len(line) size check to the completed SMTP DATA line against Server.MaxSize. An unauthenticated SMTP client can send a single line larger than the configured MaxMessageSize, causing the full line to be allocated before Mailpit returns the 552 5.3.4 rejection. This post-fix gap remains after normal multi-line DATA accumulation was bounded, and concurrent oversized lines can create substantial memory pressure beyond the configured message-size cap. This issue is fixed in version 1.30.5.","published":"2026-08-20T21:15:06.567Z","modified":"2026-08-21T11:49:03.100098581Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Go","name":"github.com/axllent/mailpit","fixedVersion":"1.30.5"}],"fix":{"url":"https://github.com/axllent/mailpit/commit/8720c6bd8281fc00d458081908f1dbef8e59a98c","label":"axllent/mailpit@8720c6b"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67447.json"},{"type":"FIX","url":"https://github.com/axllent/mailpit/commit/8720c6bd8281fc00d458081908f1dbef8e59a98c"},{"type":"WEB","url":"https://github.com/axllent/mailpit/releases/tag/v1.30.5"},{"type":"ADVISORY","url":"https://github.com/axllent/mailpit/security/advisories/GHSA-r553-m4fv-5v97"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-67447"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-21T11:49:03.100098581Z"}}