A clear "yes" from my side:
An attacker can use it to snoop kernel messages, e.g. about segfaults, kernel errors and thus use it as feedback loop for exploit optimization. Another usecase: the iptables LOG target will write to same buffer, information about connections of other users can then be misused to spoof packets with better chance for success.
I guess someone skilled will find even more ways to use dmesg to aid in privilege escalation.