{"id":"CVE-2021-3603","aliases":["BIT-phpmailer-2021-3603","GHSA-77mr-wc79-m8j3"],"url":"https://o3.security/vulnerability/CVE-2021-3603","summary":"PHPMailer untrusted code may be run from an overridden address validator","details":"PHPMailer 6.4.1 and earlier contain a vulnerability that can result in untrusted code being called (if such code is injected into the host project's scope by other means). If the $patternselect parameter to validateAddress() is set to 'php' (the default, defined by PHPMailer::$validator), and the global namespace contains a function called php, it will be called in preference to the built-in validator of the same name. Mitigated in PHPMailer 6.5.0 by denying the use of simple strings as validator function names.","published":"2021-06-17T12:15:08.150Z","modified":"2026-07-08T05:57:11.394076424Z","cvss":{"score":8.1,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":{"score":0.0226,"percentile":0.81482,"asOf":"2026-08-23"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"phpmailer/phpmailer","fixedVersion":"6.5.0"}],"fix":{"url":"https://github.com/PHPMailer/PHPMailer/commit/45f3c18dc6a2de1cb1bf49b9b249a9ee36a5f7f3","label":"PHPMailer/PHPMailer@45f3c18"},"references":[{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YRMWGA4VTMXFB22KICMB7YMFZNFV3EJ/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FJYSOFCUBS67J3TKR74SD3C454N7VTYM/"},{"type":"WEB","url":"https://www.huntr.dev/bounties/1-PHPMailer/PHPMailer/"},{"type":"FIX","url":"https://github.com/PHPMailer/PHPMailer/commit/45f3c18dc6a2de1cb1bf49b9b249a9ee36a5f7f3"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-08T05:57:11.394076424Z"}}