An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. Insufficient Cascading Style Sheets (CSS) sanitization in HTML e-mail messages may lead to a fixed-position mitigation bypass via the use of !important.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 7
https://github.com/roundcube/roundcubemail/commit/099009b9c8e1d3c636fb9a5af72f7…
cve@mitre.org
https://github.com/roundcube/roundcubemail/commit/226811a1c974271dbedca72672923…
cve@mitre.org
https://github.com/roundcube/roundcubemail/commit/57dec0c127b98e0c8e3b9c26c8004…
cve@mitre.org
https://github.com/roundcube/roundcubemail/releases/tag/1.5.14
cve@mitre.org
https://github.com/roundcube/roundcubemail/releases/tag/1.6.14
cve@mitre.org
https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5
cve@mitre.org
https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14
cve@mitre.org