Cross-Site Request Forgery (CSRF)
Poll SCM Plugin was not requiring requests to its API be sent via POST, thereby opening itself to Cross-Site Request Forgery attacks. This allowed attackers to initiate polling of projects with a known name. While Jenkins in general does not consider polling to be a protection-worthy action as it's similar to cache invalidation, the plugin specifically adds a permission to be able to use this functionality, and this issue undermines that permission.
CWE-352 - Cross-Site Request Forgery (CSRF)
Cross-Site Request Forgery (CSRF) is a vulnerability that allows an attacker to make arbitrary requests in an authenticated vulnerable web application and disrupt the integrity of the victim’s session. The impact of a successful CSRF attack may range from minor to severe, depending upon the capabilities exposed by the vulnerable application and privileges of the user. An attacker may force the user to perform state-changing requests like transferring funds, changing their email address or password etc. However, if an administrative level account is affected, it may compromise the whole web application and associated sensitive data.