In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, the modoboa driver of the password plugin could leak a Modoboa API authentication token to a user-controlled host via crafted session data. This issue only affects Roundcube instances using the password plugin with its modoboa driver.
https://roundcube.net/news/2026/08/09/security-updates-1.6.18-and-1.7.3
https://github.com/roundcube/roundcubemail/releases/tag/1.7.3
https://github.com/roundcube/roundcubemail/releases/tag/1.6.18
https://github.com/roundcube/roundcubemail/commit/b0e26d617e7bbe3051135285993bc55f718fea2f
https://github.com/roundcube/roundcubemail/commit/65b8ea9d8304b10f1d3bda5bcc82f9c682cf804c