ext/imap/php_imap.c in PHP 5.x and 7.x before 7.3.0 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via an empty string in the message argument to the imap_mail function.
Created php tracking bugs for this issue:
Affects: fedora-all [bug 1660526]
This can not affect PHP packages provided for Red Hat Enterprise Linux 7, either directly via Red Hat Enterprise Linux 7, or via Red Hat Software Collections for Red Hat Enterprise Linux 7, as those packages do not include the affected imap extension.
In Red Hat Enterprise Linux 6, the php-imap package providing the imap extension is only distributed via the unsupported Optional repository. The php-imap packages included in the Red Hat Software Collections for Red Hat Enterprise Linux 6 depend on the libc-client packages, which is only distributed via the unsupported Optional repository.