View online: https://www.drupal.org/sa-contrib-2026-135 Project: Central Authentication System (CAS) Server [1] Date: 2026-September-09 Security risk: *Moderately critical* 10 ∕ 25 AC:Basic/A:None/CI:None/II:None/E:Theoretical/TD:All [2] Vulnerability: Open redirect Affected versions: <2.0.4 || >=2.1.0 <2.1.3 CVE IDs: CVE-2026-87937 Description:  This module enables you to turn a Drupal install into the Central Authentication System (CAS) Server. It makes your database the primary location for other systems to use for authentication in a SSO environment. The module doesn't sufficiently check the service URL used to redirect the user during logout, leading to an open redirect. This vulnerability is mitigated by the fact that an attacker must convince a user to click a specially crafted link. The vulnerability cannot be exploited without user interaction and does not allow an attacker to directly compromise the CAS server or bypass authentication. Solution:  Install the latest version of Central Authentication System (CAS) Server module: * If you use the 2.0.x branch, upgrade to CAS Server 2.0.4 [3]. * If you use the 2.1.x branch, upgrade to CAS Server 2.1.3 [4] Reported By:  * Kalle Kipinä (kekkis) [5] Fixed By:  * Ted Cooper (elc) [6] Coordinated By:  * Bram Driesen (bramdriesen) [7] of the Drupal Security Team * Greg Knaddison (greggles) [8] of the Drupal Security Team * Jess (xjm) [9] of the Drupal Security Team * Swan Kalata (akalata) [10] of the Drupal Security Team ------------------------------------------------------------------------------ Contribution record [11] [1] https://www.drupal.org/project/cas_server [2] https://www.drupal.org/security-team/risk-levels [3] https://www.drupal.org/project/cas_server/releases/2.0.4 [4] https://www.drupal.org/project/cas_server/releases/2.1.3 [5] https://www.drupal.org/u/kekkis [6] https://www.drupal.org/u/elc [7] https://www.drupal.org/u/bramdriesen [8] https://www.drupal.org/u/greggles [9] https://www.drupal.org/u/xjm [10] https://www.drupal.org/u/akalata [11] https://new.drupal.org/contribution-record?source_link=https%3A//www.drupal....