Jenkins Slack Upload Plugin 1.7 and earlier stores a secret unencrypted in job config.xml files on the Jenkins master where it can be viewed by users with Extended Read permission, or access to the master file system.
https://jenkins.io/security/advisory/2020-07-02/#SECURITY-1627
https://jenkins.io/security/advisory/2020-07-02/#SECURITY-1627
http://www.openwall.com/lists/oss-security/2020/07/02/7
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-2208