Bug 2517409 (CVE-2026-74998)

Summary: CVE-2026-74998 roundcubemail: information disclosure or XSS via MIME sniffing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Roundcube Webmail. Responses from the Cascading Style Sheets (CSS) proxy were not properly validated. This could allow a remote attacker to exploit MIME sniffing vulnerabilities, resulting in information disclosure or Cross-Site Scripting (XSS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2522977, 2522981    
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Description OSIDB Bzimport 2026-08-17 13:01:22 UTC
In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, responses from the CSS (Cascading Style Sheets) proxy were not validated, which may result in information disclosure or XSS (cross-site scripting) via MIME sniffing.