CVE-2026-74999 Roundcube CVE debrief

Who should care

System administrators and security teams responsible for Roundcube Webmail installations should prioritize applying patches to mitigate this vulnerability. Additionally, operators and platform administrators should review the vulnerability's impact on their systems and take necessary actions to prevent exploitation. Vulnerability management and security teams should also be aware of the potential risks and ensure that proper security measures are in place.

Technical summary

The 'Add to address book' action in Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3 is vulnerable to stored XSS. This medium-severity vulnerability requires user interaction and can result in limited confidentiality and integrity impacts. The vulnerability is caused by inadequate input validation and output encoding, allowing an attacker to inject malicious code. To mitigate this vulnerability, it is essential to apply vendor patches and implement compensating controls.

Defensive priority

Medium-priority defensive actions recommended due to stored XSS vulnerability in Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3.

Recommended defensive actions

• Apply vendor patches to upgrade to Roundcube Webmail version 1.6.18 or 1.7.3
• Implement compensating controls such as input validation and output encoding
• Monitor for suspicious activity and exception tracking
• Review system logs for potential exploitation attempts
• Verify patch deployment and configuration
• Conduct regular security audits to identify potential vulnerabilities
• Implement asset inventory management to track affected systems

Evidence notes

Evidence from official CVE and NVD sources indicates a stored XSS vulnerability in Roundcube Webmail. Vendor patches are available in versions 1.6.18 and 1.7.3. Additional verification tasks include reviewing system logs for suspicious activity, ensuring input validation and output encoding are properly configured, and monitoring for potential exploitation attempts. It is essential to prioritize patching due to the medium severity of this vulnerability.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.