The ip6gre_err function in net/ipv6/ip6_gre.c in the Linux kernel allows remote attackers to have unspecified impact via vectors involving GRE flags in an IPv6 packet, which trigger an out-of-bounds access.
Linux Kernel 6.x/5.15 LTS
Exploit
CVE-2017-5897
NVD
Refer to CVE-2017-5897 NVD advisory