Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not implement any restrictions for the URL rendering a formatted preview of markup passed as a query parameter, resulting in a reflected cross-site scripting (XSS) vulnerability if the configured markup formatter does not prohibit unsafe elements (JavaScript) in markup.
https://www.jenkins.io/security/advisory/2021-01-13/#SECURITY-2153
Source: MITRE
Published: 2021-01-13
Updated: 2021-01-15
Type: CWE-79
Base Score: 4.3
Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N
Impact Score: 2.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 6.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Impact Score: 2.7
Exploitability Score: 2.8
Severity: MEDIUM