The Jenkins 2.73.1 and earlier, 2.83 and earlier default form control for passwords and other secrets, <f:password/>, supports form validation (e.g. for API keys). The form validation AJAX requests were sent via GET, which could result in secrets being logged to a HTTP access log in non-default configurations of Jenkins, and made available to users with access to these log files. Form validation for <f:password/> is now always sent via POST, which is typically not logged.

References

• https://nvd.nist.gov/vuln/detail/CVE-2017-1000401
• https://jenkins.io/security/advisory/2017-10-11/
• jenkinsci/jenkins@09d6046
• https://github.com/jenkinsci/jenkins/blob/6d179998e18adfbaa4e443c7e837135bf36c53d7/test/src/test/java/lib/form/PasswordTest.java