Inaccurate Suricata ET rule (SID: 2030388, CVE-2020-11900)

I found too many event on suricata after recent update regarding this rule:

alert ip any any -> any any (msg:"ET EXPLOIT Possible CVE-2020-11900 IP-in-IP tunnel Double-Free"; ip_proto:4; metadata: former_category EXPLOIT; reference:url,; classtype:attempted-admin; sid:2030388; rev:1; metadata:signature_severity Major, created_at 2020_06_22, performance_impact Significant, updated_at 2020_06_22;) 

This is strange because it match with all packets with IPIP protocol (ip_proto:4)!! Also i found another rule from Carnegie Mellon University’s CERT (link):

alert ip any any -> any any (msg:"VU#257161:CVE-2020-11900 IP-in-IP tunnel Double-Free"; ip_proto:4; sid:1370257161; rev:1;) 

But same issue is exists here!