An session fixation vulnerability exists in Jenkins GitHub Authentication Plugin 0.29 and earlier in GithubSecurityRealm.java that allows unauthorized attackers to impersonate another user if they can control the pre-authentication session.

An exposure of sensitive information vulnerability exists in Jenkins GitHub Authentication Plugin 0.29 and earlier in GithubSecurityRealm/config.jelly that allows attackers able to view a Jenkins administrator's web browser output, or control the browser (e.g. malicious extension) to retrieve the configured client secret.