Vulnerability in Roundcube Webmail
CVE-2026-35540
An issue was discovered in Roundcube Webmail 1.6.0 before 1.6.14. Insufficient Cascading Style Sheets (CSS) sanitization in HTML e-mail messages may lead to SSRF or Information Disclosure, e.g., if stylesheet links point to local network h…
EPSS: 0.000 (4.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N.
Affected products
- Roundcube Webmail — versions 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/579b68eff90650a5c782e153debd66c765648…
- github.com/roundcube/roundcubemail/releases/tag/1.6.14
- github.com/roundcube/roundcubemail/commit/27ec6cc9cb25e1ef8b4d4ef39ce76d619caa6…
Frequently asked questions
- What is CVE-2026-35540?
- CVE-2026-35540 is a medium-severity vulnerability in Roundcube Webmail, classified under Incorrect Resource Transfer Between Spheres. CVSS score: 5.4/10. Published 2026-04-03.
- How severe is CVE-2026-35540?
- Medium severity. CVSS v3 base score is 5.4 out of 10.