In Roundcube Webmail before 1.6.17 and 1.7.x before 1.7.2, insufficient Cascading Style Sheets (CSS) sanitization in HTML e-mail messages may lead to SSRF or Information Disclosure, e.g., if stylesheet links point to local network hosts. NOTE: this issue exists because of insufficient fixes for CVE-2026-35540 and CVE-2026-48843.
The CVSS severity warrants an early asset and exposure review.
In Roundcube Webmail before 1.6.17 and 1.7.x before 1.7.2, insufficient Cascading Style Sheets (CSS) sanitization in HTML e-mail messages may lead to SSRF or Information Disclosure, e.g., if stylesheet links point to local network hosts. NOTE: this issue exists because of insufficient fixes for CVE-2026-35540 and CVE-2026-48843.
Confirm exposure before applying a vendor-supported change.
Confirm that Roundcube Webmail, webmail and an affected version are present.
Combine exploitation signals with asset exposure and business criticality.
Follow the vendor advisory or supported update path and preserve rollback options.
Recheck the version, service health, access paths, and relevant logs.
