Bug 2454726 (CVE-2026-35544)

Summary: CVE-2026-35544 roundcubemail: Roundcube Webmail: Security mitigation bypass via insufficient CSS sanitization
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Roundcube Webmail. Insufficient sanitization of Cascading Style Sheets (CSS) in HTML email messages allows a remote attacker to bypass fixed-position mitigations. This can lead to a bypass of security controls designed to prevent certain types of attacks.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2454792, 2454793    
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Description OSIDB Bzimport 2026-04-03 05:02:17 UTC
An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. Insufficient Cascading Style Sheets (CSS) sanitization in HTML e-mail messages may lead to a fixed-position mitigation bypass via the use of !important.