View online: https://www.drupal.org/sa-contrib-2026-081 Project: Internationalization Single Sign-On [1] Date: 2026-July-22 Security risk: *Critical* 15 ∕ 25 AC:Complex/A:None/CI:Some/II:Some/E:Theoretical/TD:All [2] Vulnerability: Access bypass Affected versions: <1.8.0 CVE IDs: CVE-2026-16639 Description:  In a scenario of a multilingual website with different domain names per language, this module enables you to be automatically connected across the language domains if you are logged on the main language domain. The module doesn't sufficiently validate a short-lived token, allowing an attacker to bypass access control and authenticate as a victim user. This vulnerability is mitigated by the fact that an attacker must appear to originate from the same client IP as the victim. Solution:  Install the latest version: * If you use the Internationalization Single Sign-On module upgrade to i18n_sso 8.x-1.8 [3] Reported By:  * Drew Webber (mcdruid) [4] of the Drupal Security Team Fixed By:  * Florent Torregrosa (grimreaper) [5] * Drew Webber (mcdruid) [6] of the Drupal Security Team Coordinated By:  * Bram Driesen (bramdriesen) [7] of the Drupal Security Team * Greg Knaddison (greggles) [8] of the Drupal Security Team * Drew Webber (mcdruid) [9] of the Drupal Security Team * Juraj Nemec (poker10) [10] of the Drupal Security Team ------------------------------------------------------------------------------ Contribution record [11] [1] https://www.drupal.org/project/i18n_sso [2] https://www.drupal.org/security-team/risk-levels [3] https://www.drupal.org/project/i18n_sso/releases/8.x-1.8 [4] https://www.drupal.org/u/mcdruid [5] https://www.drupal.org/u/grimreaper [6] https://www.drupal.org/u/mcdruid [7] https://www.drupal.org/u/bramdriesen [8] https://www.drupal.org/u/greggles [9] https://www.drupal.org/u/mcdruid [10] https://www.drupal.org/u/poker10 [11] https://new.drupal.org/contribution-record?source_link=https%3A//www.drupal....