CVE-2026-9818
MEDIUM
NVD
CVSS Score
4.7
Severity
MEDIUM
Published
May 28, 2026
Vendor
unknown
Description
Roundcube's HTML sanitization path for message rendering allows loopback, localhost, RFC1918, link-local, and ULA URLs even when remote content loading is disabled. A remote attacker can send an HTML email that causes the victim's browser to issue requests to local or private-network services simply by opening the message preview.
References
- https://advisories.orangecyberdefense.com/advisories/163
- https://github.com/roundcube/roundcubemail/commit/7b52353653a67e6073b97d70eb94047132b78556
- https://github.com/roundcube/roundcubemail/commit/faf867432f51ebbe100382a70a9e3c042415ee1b
- https://github.com/roundcube/roundcubemail/releases/tag/1.6.16
- https://github.com/roundcube/roundcubemail/releases/tag/1.7.1