Home/CVE/An issue was discovered in Roundcube Webmail 1.6.0 before 1.6.14. Insufficient Cascading Style Sheets (CSS) sanitization
CVE

CVE-2026-35540

An issue was discovered in Roundcube Webmail 1.6.0 before 1.6.14. Insufficient Cascading Style Sheets (CSS) sanitization

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.

MEDIUM · CVSS 5.4 EPSS 0.00017
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-669Incorrect Resource Transfer Between Spheres
▤

Affected Products & Versions

1
roundcube webmail>= 1.6.0 and < 1.6.14
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Packagist roundcube/roundcubemail MEDIUM fixed in 1.7-rc5
▣

Scoring & Timeline

5.4
MEDIUM · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD03 Apr 2026 · 05:16 AM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

5
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/roundcube/roundcubemail/commit/27ec6cc9cb25e1ef8b4d4ef39ce76d619caa6870Patch
https://github.com/roundcube/roundcubemail/commit/579b68eff90650a5c782e153debd66c765648942Patch
https://github.com/roundcube/roundcubemail/releases/tag/1.6.14Release Notes
https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5Release Notes
https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14Vendor Advisory
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