GNU patch through 2.7.6 is vulnerable to OS shell command injection that can be exploited by opening a crafted patch file that contains an ed style diff payload with shell metacharacters. The ed editor does not need to be present on the vulnerable system. This is different from CVE-2018-1000156.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.034
EPSS Ranking 86.9%