Advisory Weakness Curation

PHPMailer untrusted code may be run from an overridden address validator If a function is defined that has the same name as the default built-in email address validation scheme (`php`), it will be called in default configuration as when no validation scheme is provided, the default scheme's callable `php` was being called. If an attacker is able to inject such a function into the application (a much bigger issue), it will be called whenever an email address is validated, such as when calling `validateAddress()`. ### Impact Low impact – exploitation requires that an attacker can already inject code into an application, but it provides a trigger pathway. ### Patches This is patched in PHPMailer 6.5.0 by denying the use of simple strings as validator function names, which is a very minor BC break. ### Workarounds Inject your own email validator function. ### References Reported by [Vikrant Singh Chauhan](mailto:vi@hackberry.xyz) via huntr.dev https://www.huntr.dev/. CVE-2021-3603 https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-3603 ### For more information If you have any questions or comments about this advisory: * Open an issue in the PHPMailer project https://github.com/PHPMailer/PHPMailer * [Email us](mailto:phpmailer@synchromedia.co.uk).

Inclusion of Functionality from Untrusted Control Sphere PHPMailer 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).