Critical Roundcube Vulnerabilities Expose Users to Malicious Script Execution
Roundcube Webmail, a widely used open-source email client, has recently addressed two critical security vulnerabilities affecting its 1.6 and 1.5 LTS versions. These flaws could allow attackers to execute malicious scripts and gain unauthorized access to sensitive information through various attack vectors.
Cross-Site Scripting (XSS) Vulnerability in SVG Handling
The first vulnerability involves a Cross-Site Scripting (XSS) flaw within Roundcube’s handling of Scalable Vector Graphics (SVG) files. Attackers can exploit the SVG ‘animate’ tag to inject and execute arbitrary JavaScript code within the webmail interface. This vulnerability, reported by security researcher Valentin T. from CrowdStrike, poses a significant risk to webmail users. Successful exploitation could enable attackers to steal session tokens, credentials, and sensitive email data.
Information Disclosure via HTML Sanitizer Bypass
The second vulnerability pertains to an Information Disclosure flaw in Roundcube’s HTML style sanitizer. Reported by security researcher somerandomdev, this issue could allow attackers to bypass sanitization filters and access confidential information through specially crafted HTML content. The flaw in the sanitization logic creates a pathway for information leakage, potentially compromising user privacy.
Technical Details and Affected Versions
The vulnerabilities are identified as follows:
– CVE-2024-XXXXX: Cross-Site Scripting (XSS) vulnerability affecting versions 1.6.x and 1.5.x LTS. This flaw allows information disclosure through HTML-style sanitizer bypassing filters.
– CVE-2024-XXXXX: Information Disclosure vulnerability affecting versions 1.6.x and 1.5.x LTS. This issue permits information disclosure via HTML style sanitizer bypassing filters.
Immediate Action Required
Roundcube has released patched versions addressing both vulnerabilities and strongly recommends immediate updates for all productive installations running versions 1.6.x and 1.5.x. System administrators should prioritize deploying versions 1.6.12 and 1.5.12 to eliminate exploitation risks. The updated versions are available on GitHub’s official Roundcube repository.
Users should verify their current Roundcube version and apply updates without delay, as these vulnerabilities could be actively exploited in the wild. Organizations relying on Roundcube for email services should treat this update as critical infrastructure maintenance.
Broader Implications and Historical Context
These vulnerabilities are part of a series of security issues that have affected Roundcube in recent years. For instance, a decade-old critical security vulnerability (CVE-2025-49113) was discovered, allowing authenticated attackers to execute arbitrary code on vulnerable systems, potentially affecting millions of installations worldwide. This flaw carried an alarming CVSS score of 9.9 out of 10.0, marking it as one of the most severe vulnerabilities discovered in recent years. The vulnerability affected all Roundcube Webmail versions before 1.5.10 and 1.6.x before 1.6.11, representing a staggering scope of impact that included over 53 million hosts globally. The flaw particularly concerned popular web hosting control panels such as cPanel, Plesk, ISPConfig, and DirectAdmin, which bundle Roundcube as their default webmail solution.
Additionally, a critical Cross-Site Scripting (XSS) vulnerability (CVE-2024-57004) was discovered in Roundcube Webmail version 1.6.9. This flaw allowed remote authenticated users to upload malicious files disguised as email attachments, posing significant risks to individuals and organizations using the popular open-source webmail client. The vulnerability stemmed from insufficient sanitization of user input during the handling of email attachments. Attackers could exploit this flaw by uploading a malicious file as an attachment to an email, which was then stored in the SENT folder. When a victim accessed this folder, the embedded script within the malicious file executed in their browser, leading to unauthorized access to sensitive data or further exploitation of the user’s account.
Furthermore, a critical vulnerability in Roundcube Webmail allowed authenticated attackers to execute arbitrary code remotely. The vulnerability, discovered through PHP object deserialization flaws, affected all installations running versions 1.6.x and 1.5.x. Security researcher firs0v reported the flaw, prompting immediate patches in versions 1.6.11 and 1.5.10 released on June 1, 2025. Organizations worldwide were urged to implement these updates immediately to prevent potential system compromises.
Mitigation and Best Practices
To mitigate the risks associated with these vulnerabilities, organizations should:
1. Update Roundcube Installations: Ensure that all Roundcube installations are updated to the latest versions (1.6.12 and 1.5.12) to address the identified vulnerabilities.
2. Monitor for Unusual Activity: Regularly monitor email server logs and user activities for signs of unauthorized access or unusual behavior.
3. Educate Users: Train users to recognize phishing attempts and the importance of not interacting with suspicious emails or attachments.
4. Implement Security Measures: Utilize web application firewalls (WAFs) and intrusion detection systems (IDS) to detect and prevent exploitation attempts.
5. Regular Security Audits: Conduct periodic security assessments to identify and remediate potential vulnerabilities within the organization’s infrastructure.
Conclusion
The recent vulnerabilities in Roundcube Webmail underscore the critical importance of timely software updates and proactive security measures. Organizations must remain vigilant and ensure that their systems are protected against potential exploitation. By promptly applying the latest patches and adhering to best security practices, users can safeguard their email communications and sensitive information from malicious actors.
