CVE-2026-35544

EUVD-2026-18591
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 28%
Affected Products (NVD)
VendorProductVersion
roundcubewebmail
𝑥
≤ 1.5.13
roundcubewebmail
1.6.0 ≤
𝑥
≤ 1.6.13
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
roundcube
bookworm
1.6.5+dfsg-1+deb12u8
fixed
bookworm (security)
1.6.5+dfsg-1+deb12u9
fixed
bullseye
vulnerable
bullseye (security)
1.4.15+dfsg.1-1+deb11u9
fixed
forky
1.6.16+dfsg-1
fixed
sid
1.6.16+dfsg-1
fixed
trixie
1.6.15+dfsg-0+deb13u1
fixed
trixie (security)
1.6.16+dfsg-0+deb13u1
fixed
Common Weakness Enumeration
References
https://github.com/roundcube/roundcubemail/commit/099009b9c8e1d3c636fb9a5af72f7c2596018662
https://github.com/roundcube/roundcubemail/commit/226811a1c974271dbedca72672923abaff8191c0
https://github.com/roundcube/roundcubemail/commit/57dec0c127b98e0c8e3b9c26c80049b9c4bcaea7
https://github.com/roundcube/roundcubemail/releases/tag/1.5.14
https://github.com/roundcube/roundcubemail/releases/tag/1.6.14
https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5
https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14