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.
References:- https://nvd.nist.gov/vuln/detail/CVE-2019-10405
- https://jenkins.io/security/advisory/2019-09-25/#SECURITY-1505
- http://www.openwall.com/lists/oss-security/2019/09/25/3
- https://github.com/jenkinsci/jenkins/commit/560ee832b41814660c5632ea36ad1a1c977177bf
- https://github.com/advisories/GHSA-47wc-p5cp-w7pw