XSS in Roundcube Webmail
CVE-2026-35539
An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. XSS exists because of insufficient HTML attachment sanitization in preview mode. A victim must preview a text/html attachment.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.000 (2.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/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/1b30edf5369668c92fe91dae3d52e477c808a…
- github.com/roundcube/roundcubemail/releases/tag/1.6.14
- github.com/roundcube/roundcubemail/commit/10a6d1fa8acac85c727b0a6ae4a6642bfa27b…
- github.com/roundcube/roundcubemail/releases/tag/1.5.14
- github.com/roundcube/roundcubemail/commit/d742954ccbcdee7020f8f2e7c49ce0fca5a0e…
Frequently asked questions
- What is CVE-2026-35539?
- CVE-2026-35539 is a medium-severity vulnerability in Roundcube Webmail, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-04-03.
- How severe is CVE-2026-35539?
- Medium severity. CVSS v3 base score is 6.1 out of 10.