Roundcube Vulnerabilities Allow Attackers to Execute Malicious Scripts

Roundcube, a popular open-source webmail platform used by organizations worldwide, has released critical security updates to fix two serious vulnerabilities.

The flaws affect versions 1.6 and 1.5 LTS and could allow attackers to run harmful scripts or steal sensitive information.

The Roundcube team released these security patches on December 13, 2025, and strongly recommends all users update immediately.

The first vulnerability is a Cross-Site Scripting (XSS) flaw. This security weakness exists in how Roundcube handles SVG images, particularly the animate tag.

Attackers could exploit this flaw to inject malicious scripts into the webmail interface, potentially compromising user accounts and stealing sensitive emails.

The second issue is an Information Disclosure vulnerability in the HTML style sanitizer. This component is designed to clean up HTML emails and remove dangerous code.

However, a weakness in this sanitizer could allow attackers to bypass the security controls and access data that should remain protected. Security researcher “somerandomdev” discovered this flaw.

While information disclosure vulnerabilities are typically less dangerous than remote code execution attacks, they can be combined with other exploits to cause more serious damage to systems.

Impact and Risk

Roundcube is widely used for email access, making it a valuable target for attackers. Webmail clients like Roundcube are often the first entry point into an organization’s network.

If not properly secured, these vulnerabilities could expose thousands of users to attacks.

Hackers could exploit the XSS vulnerability to steal login credentials, redirect users to phishing sites, or inject tracking code into emails.

The information disclosure flaw could expose internal data, usernames, or other confidential information.

The Roundcube team has urged all administrators running version 1.6. x and 1.5. x to update immediately.

The new secure versions are 1.6.12 and 1.5.12, which contain fixes for both vulnerabilities.

Administrators can find the complete update information and download links on the official Roundcube GitHub release pages.

The update process is straightforward and should be completed promptly to protect users from potential attacks.

Why This Matters

Email remains a critical communication tool for businesses and individuals. Keeping webmail software up to date is essential for protecting sensitive information.

These vulnerabilities highlight the importance of regular security updates and monitoring.

Organizations should prioritize patching their Roundcube installations immediately. Delaying updates could leave systems vulnerable to targeted attacks that steal email and compromise user accounts.

Users of Roundcube webmail should confirm with their administrators that their systems are up to date to ensure their email remains secure.

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