CVE-2010-0464 in webmail
Summary
by MITRE
Roundcube 0.3.1 and earlier does not request that the web browser avoid DNS prefetching of domain names contained in e-mail messages, which makes it easier for remote attackers to determine the network location of the webmail user by logging DNS requests.
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Analysis
by VulDB Data Team • 04/29/2026
The vulnerability described in CVE-2010-0464 represents a significant privacy and security concern within the Roundcube webmail application ecosystem. This flaw exists in versions 0.3.1 and earlier, where the application fails to implement proper browser directives that would prevent DNS prefetching of domain names embedded within email messages. The issue stems from the application's lack of awareness regarding browser security mechanisms and its failure to enforce protective measures that could otherwise mitigate reconnaissance activities by malicious actors.
The technical nature of this vulnerability lies in the absence of the dns-prefetch directive in HTTP response headers or HTML markup generated by Roundcube. When users view emails containing links to external domains, modern web browsers automatically perform DNS resolution in the background to improve page load times. However, this behavior inadvertently creates a fingerprinting opportunity where attackers can monitor DNS requests to identify which domains users are accessing, thereby mapping their email activity patterns and potentially revealing sensitive information about their network environment and online behavior. This flaw directly relates to CWE-200, which addresses information exposure through improper access control and information leakage.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential network reconnaissance and targeted attacks. Remote attackers can exploit this weakness by monitoring DNS queries from a victim's browser, effectively mapping out the email domains that user interacts with. This information can be leveraged to identify business contacts, personal relationships, or sensitive organizational structures. The vulnerability creates a passive reconnaissance channel that allows threat actors to gather intelligence about user behavior without requiring direct interaction with the target system, making it particularly dangerous for users in high-risk environments. This aligns with ATT&CK technique T1082, which involves system information discovery, and T1592, which covers reconnaissance through information gathering.
Mitigation strategies for this vulnerability require both application-level and network-level interventions. The primary solution involves updating Roundcube installations to versions that properly implement browser security headers and disable DNS prefetching for email content. Administrators should ensure that the web server configuration includes appropriate HTTP headers such as the dns-prefetch control directive to prevent automatic DNS resolution of external domains. Additionally, network administrators should implement DNS monitoring and logging to detect unusual patterns that might indicate this type of reconnaissance activity. Organizations should also consider implementing network-level controls that limit DNS resolution requests from email clients to prevent information leakage through DNS queries. The vulnerability demonstrates the importance of considering browser security features in web application development and highlights the need for comprehensive security testing that includes evaluation of client-side behavior and information exposure risks.