Jenkins Mailer Plugin 1.32 and earlier does not perform hostname validation when connecting to the configured SMTP server.
http://www.openwall.com/lists/oss-security/2020/09/16/3
https://www.jenkins.io/security/advisory/2020-09-16/#SECURITY-1813
Source: MITRE
Published: 2020-09-16
Updated: 2020-09-18
Type: CWE-295
Base Score: 5.8
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:N
Impact Score: 4.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 4.8
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Impact Score: 2.5
Exploitability Score: 2.2
Severity: MEDIUM