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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.005 (40.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001
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 (Vendor Advisory)
- github.com/roundcube/roundcubemail/releases/tag/1.7-rc5 (Release Notes)
- github.com/roundcube/roundcubemail/commit/226811a1c974271dbedca72672923abaff819… (Patch)
- github.com/roundcube/roundcubemail/releases/tag/1.6.14 (Release Notes)
- github.com/roundcube/roundcubemail/commit/099009b9c8e1d3c636fb9a5af72f7c2596018… (Patch)
- github.com/roundcube/roundcubemail/releases/tag/1.5.14 (Release Notes)
- github.com/roundcube/roundcubemail/commit/57dec0c127b98e0c8e3b9c26c80049b9c4bca… (Patch)
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.