Bug 2454720 (CVE-2026-35539)

Summary: CVE-2026-35539 roundcubemail: Roundcube Webmail: Cross-Site Scripting via HTML attachment preview
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. This cross-site scripting (XSS) vulnerability arises from insufficient sanitization of HTML attachments when viewed in preview mode. A remote attacker could send a specially crafted HTML attachment, which, if previewed by a victim, could lead to the execution of malicious scripts in the victim's web browser. This could result in information disclosure or other unauthorized actions within the user's session.
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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 05:01:50 UTC
An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. XSS exists because of insufficient HTML attachment sanitization in preview mode. A victim must preview a text/html attachment.