CVE-2008-4033 in XML Core Services
Summary
by MITRE
Cross-domain vulnerability in Microsoft XML Core Services 3.0 through 6.0, as used in Microsoft Expression Web, Office, Internet Explorer, and other products, allows remote attackers to obtain sensitive information from another domain and corrupt the session state via HTTP request header fields, as demonstrated by the Transfer-Encoding field, aka "MSXML Header Request Vulnerability."
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Analysis
by VulDB Data Team • 06/14/2025
The CVE-2008-4033 vulnerability represents a significant cross-domain information disclosure and session corruption flaw within Microsoft XML Core Services versions 3.0 through 6.0. This vulnerability specifically affects Microsoft Expression Web, Office applications, and Internet Explorer, creating a dangerous attack surface that enables remote adversaries to manipulate HTTP request headers and exploit the underlying MSXML parsing mechanisms. The vulnerability stems from improper handling of HTTP header fields, particularly the Transfer-Encoding field, which allows attackers to craft malicious requests that can bypass normal security boundaries between domains. The flaw operates at the core level of XML processing, where MSXML fails to properly validate or sanitize header values before processing them, creating opportunities for cross-domain data leakage and session manipulation.
The technical implementation of this vulnerability leverages the MSXML HTTP request processing pipeline, where the system incorrectly interprets certain HTTP header values, particularly those related to transfer encoding, as legitimate request parameters. When an attacker crafts a malicious HTTP request containing specially formatted Transfer-Encoding headers, the MSXML component processes these headers without adequate validation, allowing unauthorized access to resources across domain boundaries. This behavior creates a path for attackers to extract sensitive information from other domains and potentially corrupt session state information, as the system fails to enforce proper cross-domain security policies during header processing. The vulnerability is particularly dangerous because it operates at the HTTP protocol level, where MSXML serves as a middleware component that processes requests before they reach the application layer, making it difficult to detect and prevent through traditional application-level security controls.
The operational impact of CVE-2008-4033 extends beyond simple information disclosure, as it enables session hijacking and cross-site request forgery attacks that can compromise user authentication and authorization mechanisms. Attackers can exploit this vulnerability to gain unauthorized access to user sessions, potentially leading to complete account compromise and unauthorized data access. The vulnerability affects multiple Microsoft products simultaneously, amplifying its potential impact across various attack vectors including web applications, email clients, and content management systems. From a cybersecurity perspective, this vulnerability represents a critical weakness in Microsoft's security architecture, as it allows attackers to bypass domain isolation mechanisms that are fundamental to web security models. The vulnerability's exploitation requires minimal technical expertise, making it particularly dangerous for widespread abuse in automated attack scenarios.
Organizations affected by this vulnerability should implement immediate mitigations including patching MSXML components to the latest versions, implementing proper HTTP header validation at network boundaries, and deploying web application firewalls to filter malicious header values. The vulnerability aligns with CWE-200 (Information Exposure) and CWE-345 (Insufficient Verification of Data Authenticity) classifications, while also mapping to ATT&CK techniques involving credential access and privilege escalation through protocol manipulation. Network segmentation and proper access controls should be enforced to limit the potential impact of successful exploitation, particularly in environments where MSXML is used for processing untrusted input. Security monitoring should focus on detecting unusual HTTP header patterns, especially those involving Transfer-Encoding fields, as potential indicators of exploitation attempts. The vulnerability highlights the importance of proper input validation and the need for robust security controls at multiple layers of the application stack to prevent cross-domain attacks that exploit protocol-level weaknesses in core infrastructure components.