Vulnerability in Roundcube Webmail
CVE-2026-35544
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.
EPSS: 0.000 (3.1th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
Affected products
- Roundcube Webmail — versions 0, 1.6.0
Weakness classification (CWE)
References
- roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14
- github.com/roundcube/roundcubemail/releases/tag/1.7-rc5
- github.com/roundcube/roundcubemail/commit/226811a1c974271dbedca72672923abaff819…
- github.com/roundcube/roundcubemail/releases/tag/1.6.14
- github.com/roundcube/roundcubemail/commit/099009b9c8e1d3c636fb9a5af72f7c2596018…
- github.com/roundcube/roundcubemail/releases/tag/1.5.14
- github.com/roundcube/roundcubemail/commit/57dec0c127b98e0c8e3b9c26c80049b9c4bca…
Frequently asked questions
- What is CVE-2026-35544?
- CVE-2026-35544 is a medium-severity vulnerability in Roundcube Webmail, classified under Incorrect Resource Transfer Between Spheres. CVSS score: 5.3/10. Published 2026-04-03.
- How severe is CVE-2026-35544?
- Medium severity. CVSS v3 base score is 5.3 out of 10.