Medium severity · published Apr 3, 2026
CVE-2026-35540
An issue was discovered in Roundcube Webmail 1.6.0 before 1.6.14
6.5
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 32% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
WE
Webmail · Roundcube
1.6.0 before 1.6.14 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-35540
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-35540
Patch
https://github.com/roundcube/roundcubemail/commit/27ec6cc9cb25e1ef8b4d4ef39ce76d619caa6870
Patch
https://github.com/roundcube/roundcubemail/commit/579b68eff90650a5c782e153debd66c765648942
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
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