CVE-2026-35540

low-risk
Published 2026-04-03

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 hosts.

Do I need to act?

-
0.04% chance of exploitation
EPSS score — low exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.4/10 Medium
NETWORK / HIGH complexity

Affected Products (1)

Affected Vendors

Roundcube

References (5)

Patch https://github.com/roundcube/roundcubemail/commit/27ec6cc9cb25e1ef8b4d4ef39ce76d...
Patch https://github.com/roundcube/roundcubemail/commit/579b68eff90650a5c782e153debd66...
Release Notes https://github.com/roundcube/roundcubemail/releases/tag/1.6.14
Release Notes https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5
Vendor Advisory https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14
22
/ 100
low-risk
Severity 17/34 · Moderate
Exploitability 0/34 · Minimal
Exposure 5/34 · Minimal