The SplObjectStorage unserialize implementation in ext/spl/spl_observer.c in PHP before 7.0.12 does not verify that a key is an object, which allows remote attackers to execute arbitrary code or cause a denial of service (uninitialized memory access) via crafted serialized data.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.032
EPSS Ranking 86.5%