CVE-2021-21637: 
Java vulnerability analysis and mitigation

CVE-2021-21637 is a high severity security vulnerability affecting the Team Foundation Server Plugin version 5.157.1 and earlier in Jenkins. The vulnerability was discovered by Daniel Beck of CloudBees, Inc. and publicly disclosed on March 30, 2021. This vulnerability is related to missing permission checks in an HTTP endpoint that affects the Jenkins automation server and its Team Foundation Server Plugin (Jenkins Advisory).

The vulnerability stems from the Team Foundation Server Plugin's failure to perform proper permission checks in an HTTP endpoint. The issue has a high severity CVSS rating. The vulnerability allows attackers with Overall/Read permission to connect to an attacker-specified URL using attacker-specified credentials IDs obtained through other methods. Additionally, the affected HTTP endpoint does not require POST requests, which compounds the security issue (Jenkins Advisory).

When exploited, this vulnerability enables attackers to capture credentials stored in Jenkins by connecting to attacker-specified URLs using credential IDs they've obtained through other means. The impact is particularly severe as it allows for the potential theft of stored credentials, which could lead to unauthorized access to various systems and resources (Jenkins Advisory).

The vulnerability requires an attacker to have Overall/Read permission in the Jenkins system. The exploit can be executed through HTTP endpoints that don't require POST requests, making it easier to exploit through cross-site request forgery (CSRF) attacks. This vulnerability is tracked alongside CVE-2021-21638, which specifically addresses the CSRF aspect of the security issue (Jenkins Advisory).

As of the advisory's publication date on March 30, 2021, no official fix was available for this vulnerability in the Team Foundation Server Plugin. Users of the affected plugin (version 5.157.1 and earlier) should monitor for updates and implement additional security controls to restrict access to the Jenkins environment (Jenkins Advisory).