Jenkins 2.196 and earlier, LTS 2.176.3 and earlier printed the value of the "Cookie" HTTP request header on the /whoAmI/ URL, allowing attackers exploiting another XSS vulnerability to obtain the HTTP session cookie despite it being marked HttpOnly.
http://www.openwall.com/lists/oss-security/2019/09/25/3
https://jenkins.io/security/advisory/2019-09-25/#SECURITY-1505
Source: MITRE
Published: 2019-09-25
Updated: 2019-10-09
Type: CWE-200
Base Score: 4
Vector: AV:N/AC:L/Au:S/C:P/I:N/A:N
Impact Score: 2.9
Exploitability Score: 8
Severity: MEDIUM
Base Score: 4.3
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Impact Score: 1.4
Exploitability Score: 2.8
Severity: MEDIUM