CVE-2010-0463 in IMP
Summary
by MITRE
Horde IMP 4.3.6 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-2010-0463 affects Horde IMP versions 4.3.6 and earlier, representing a significant privacy and security concern within web-based email systems. This issue stems from the application's failure to implement proper browser directives that would prevent DNS prefetching behavior when processing email content, creating a covert channel for network reconnaissance. The flaw exists at the application layer where email messages are rendered in web browsers, specifically impacting how domain names embedded in email content are handled during display operations.
The technical implementation of this vulnerability involves the absence of the dns-prefetch directive in HTTP headers or meta tags when serving email content through the Horde IMP interface. When web browsers encounter domain names within email messages, they typically perform DNS resolution in advance to improve user experience by pre-resolving hostnames. However, this automatic behavior creates a timing-based side channel attack vector where remote adversaries can monitor DNS requests to infer information about the email user's network activities and potentially map their network topology. The vulnerability is classified under CWE-200 as "Information Exposure" and specifically relates to "Information Exposure Through DNS Queries" which aligns with the broader category of information leakage attacks.
The operational impact of this vulnerability extends beyond simple privacy concerns to potentially enable more sophisticated reconnaissance activities. Attackers can correlate DNS query patterns with email traffic to build profiles of user behavior, identify network infrastructure, and potentially map internal network structures. This information can be particularly valuable for attackers planning targeted attacks or conducting network reconnaissance before launching more serious threats. The vulnerability affects the principle of least privilege by exposing additional network information beyond what is necessary for legitimate email functionality, creating an information disclosure channel that violates standard security practices.
This vulnerability demonstrates a fundamental flaw in web application security where the application fails to properly control browser behavior and implement appropriate security headers. The attack vector is particularly concerning because it operates at the user interaction level where adversaries can leverage legitimate email browsing activities to gather intelligence. Security professionals should consider this vulnerability in relation to the ATT&CK framework's reconnaissance phase, specifically the techniques involving "Network Service Scanning" and "DNS Server Discovery" which can be facilitated through such information leakage mechanisms. Mitigation strategies should include implementing proper HTTP headers such as the dns-prefetch directive, ensuring email rendering systems properly sanitize and control browser behavior, and conducting regular security assessments to identify similar information disclosure vulnerabilities. Organizations should also consider implementing network monitoring solutions that can detect anomalous DNS query patterns that may indicate exploitation attempts.