Weakness
In Roundcube Webmail 1.6.x between 1.6.14 and 1.6.16 and 1.7.x before 1.7.1, remote image blocking was not honored for URLs pointing to local/private destinations, which may lead to information disclosure or privilege escalation via a text/html email message.
References
- https://github.com/roundcube/roundcubemail/commit/7b52353653a67e6073b97d70eb94047132b78556
- https://github.com/roundcube/roundcubemail/commit/d82b8c6cd06c378eca6d647ccd548f4ff1c68659
- https://github.com/roundcube/roundcubemail/releases/tag/1.6.16
- https://github.com/roundcube/roundcubemail/releases/tag/1.7.1
- https://roundcube.net/news/2026/05/24/security-updates-1.6.16-and-1.7.1
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