Advisory Weakness Curation

Remote Code Execution vulnerability in PHPMailer 6.4.1 running on Windows PHPMailer 6.4.1 contains a possible remote code execution vulnerability through the `$lang_path` parameter of the `setLanguage()` method. If the `$lang_path` parameter is passed unfiltered from user input, it can be set to a UNC path https://docs.microsoft.com/en-us/dotnet/standard/io/file-path-formats#unc-paths, and if an attacker is also able to create a remote mount on the server that the UNC path points to, a script file under their control may be executed. ### Impact Arbitrary code may be run by a remote attacker under the web server or PHP process running on Window hosts. ### Patches Mitigated in PHPMailer 6.5.0 by no longer treating translation files as PHP code, but by parsing their text content directly. This approach avoids the possibility of executing unknown code while retaining backward compatibility. This isn't ideal, so the current translation format is deprecated and will be replaced in the next major release. ### Workarounds Any of: * Ensure that calling code does not pass unfiltered user-supplied data to the `$lang_path` parameter of the `setLanguage()` method. * Block or filter the use of unknown UNC paths in this parameter (or altogether). * Ensure that unauthorised users do not have the ability to read from unknown remote servers via UNC paths. * Run on an OS that does not support UNC paths ### References CVE-2021-34551 https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-34551. Reported by listensec.com https://listensec.com via Tidelift. ### For more information If you have any questions or comments about this advisory: * Open an issue in PHPMailer https://github.com/PHPMailer/PHPMailer * [Email the maintainers](mailto:phpmailer@synchromedia.co.uk)

Unrestricted Upload of File with Dangerous Type PHPMailer on Windows allows remote code execution if lang_path is untrusted data and has a UNC pathname.