CVE-2007-2225 in Outlook Express
Summary
by MITRE
A component in Microsoft Outlook Express 6 and Windows Mail in Windows Vista does not properly handle certain HTTP headers when processing MHTML protocol URLs, which allows remote attackers to obtain sensitive information from other Internet Explorer domains, aka "URL Parsing Cross Domain Information Disclosure Vulnerability."
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Analysis
by VulDB Data Team • 06/22/2025
The vulnerability described in CVE-2007-2225 represents a significant cross-domain information disclosure flaw affecting Microsoft Outlook Express 6 and Windows Mail applications running on Windows Vista systems. This vulnerability stems from improper handling of HTTP headers during the processing of MHTML protocol URLs, creating a pathway for malicious actors to exploit web browser security boundaries. The flaw specifically manifests when these email clients process MHTML content that contains specially crafted URLs, allowing attackers to bypass normal security restrictions that typically prevent cross-domain data access.
The technical implementation of this vulnerability involves the manipulation of HTTP headers within MHTML protocol URLs that Outlook Express and Windows Mail process without adequate validation. When these applications encounter such malformed URLs, they fail to properly isolate domain boundaries, enabling remote attackers to construct malicious content that can extract information from different Internet Explorer domains. This behavior violates fundamental web security principles and represents a classic example of insufficient input validation and improper handling of cross-domain requests. The vulnerability is classified under CWE-20 as a weakness involving improper input validation, specifically in the context of HTTP header processing and URL parsing.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially enable attackers to access sensitive data from other domains that should normally be protected by browser security mechanisms. An attacker could leverage this vulnerability by crafting malicious emails containing specially formatted MHTML content that, when opened by a victim using the vulnerable email client, would allow extraction of cookies, session information, or other sensitive data from different web domains. This creates a vector for credential theft, session hijacking, and potentially more sophisticated attacks that could escalate to full system compromise. The attack requires minimal user interaction beyond opening the malicious email, making it particularly dangerous in phishing scenarios.
The attack pattern associated with this vulnerability aligns with techniques documented in the MITRE ATT&CK framework under the T1190 category for "Exploit Public-Facing Application" and T1566 for "Phishing" as the initial access vector. Security professionals should consider this vulnerability as part of a broader threat landscape involving client-side exploitation techniques that target email applications. Organizations should implement layered defenses including email filtering solutions, regular security updates, and user education about opening suspicious emails. The vulnerability demonstrates the importance of proper cross-domain security boundaries in client applications and highlights the need for comprehensive input validation across all application components that handle external content processing. Microsoft addressed this issue through security updates, but the vulnerability serves as a reminder of the persistent challenges in securing email clients against sophisticated cross-domain attacks.