In PHP 8.3.* before 8.3.5, function mb_encode_mimeheader() runs endlessly for some inputs that contain long strings of non-space characters followed by a space. This could lead to a potential DoS attack if a hostile user sends data to an application that uses this function.
https://security.netapp.com/advisory/ntap-20240510-0011/
https://github.com/php/php-src/security/advisories/GHSA-fjp9-9hwx-59fq