Any TCP packet (with IP options) you can send to a Linux kernel that doesn't get DROP'd by netfilter makes you technically vulnerable.

That includes the one port your LAMP stack uses.

Or, the attacker might be originating from the other side of a device, like within a LAN. Malicious employees/house guests/what-have-you could target devices from inside your network where most devices (not just servers) don't have as much protection and often have other open ports accessible, like file sharing/SMB, SSH, SMTP, RDP, databases etc.