Jenkins Plugin Installation Manager Tool 2.1.3 and earlier does not verify plugin downloads.
https://www.jenkins.io/security/advisory/2020-12-03/#SECURITY-1856
https://www.jenkins.io/security/advisory/2020-12-03/#SECURITY-1856
http://www.openwall.com/lists/oss-security/2020/12/03/2
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-2320