CVE-2021-21636

Vulnerability

Description

A missing permission check in the Jenkins Team Foundation Server Plugin (versions 5.157.1 and earlier) allows attackers with Overall/Read permission to enumerate credential IDs stored in Jenkins [1][2]. The plugin fails to properly authorize access to certain API endpoints, exposing internal identifiers without requiring more privileged permissions.

Exploitation

An attacker needs only Overall/Read permission, which is a low-level privilege typically granted to many users. No further authentication or network position is required beyond Jenkins access. The enumeration can be performed remotely via crafted requests to the affected plugin endpoints [3].

Impact

By enumerating credential IDs, an attacker can identify valid credential identifiers, which may be used in subsequent attacks to reference specific credentials. While the actual secrets are not exposed directly, knowing the IDs enables targeted attacks that could exploit other vulnerabilities or social engineering [4].

Mitigation

As of the advisory date (March 30, 2021), the Jenkins security team acknowledged the issue but did not release a fix. Users are advised to restrict Overall/Read permission to trusted users only and monitor for plugin updates [2][3].