CVE-2009-2631 in StoneGate
Summary
by MITRE
Multiple clientless SSL VPN products that run in web browsers, including Stonesoft StoneGate; Cisco ASA; SonicWALL E-Class SSL VPN and SonicWALL SSL VPN; SafeNet SecureWire Access Gateway; Juniper Networks Secure Access; Nortel CallPilot; Citrix Access Gateway; and other products, when running in configurations that do not restrict access to the same domain as the VPN, retrieve the content of remote URLs from one domain and rewrite them so they originate from the VPN s domain, which violates the same origin policy and allows remote attackers to conduct cross-site scripting attacks, read cookies that originated from other domains, access the Web VPN session to gain access to internal resources, perform key logging, and conduct other attacks. NOTE: it could be argued that this is a fundamental design problem in any clientless VPN solution, as opposed to a commonly-introduced error that can be fixed in separate implementations. Therefore a single CVE has been assigned for all products that have this design.
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Analysis
by VulDB Data Team • 06/16/2025
This vulnerability represents a critical architectural flaw in clientless SSL VPN implementations that fundamentally undermines web security boundaries. The issue stems from how these systems handle cross-domain content retrieval and rewriting, creating a dangerous breach in the same origin policy that browsers enforce to protect users from malicious cross-site scripting attacks. When VPN products operate without proper domain restriction mechanisms, they inadvertently transform remote content from external domains into locally served content, effectively bypassing browser security controls that normally prevent such cross-domain interactions.
The technical exploitation occurs when clientless VPN solutions rewrite URLs from remote domains to appear as if they originate from the VPN server itself, violating the fundamental security principle that content from different domains should remain isolated from each other. This design flaw enables attackers to inject malicious scripts that can execute within the context of the VPN session, potentially accessing sensitive session cookies, user credentials, and internal network resources that would otherwise remain protected. The vulnerability affects multiple major vendors including Cisco, SonicWALL, Juniper, and others, indicating this is not an isolated implementation error but a systemic architectural weakness in how these products handle web content mediation.
The operational impact of this vulnerability extends far beyond simple cross-site scripting attacks, as it provides attackers with persistent access to internal network resources through the VPN session. Once an attacker successfully exploits this vulnerability, they can establish keylogging capabilities, access sensitive data, and potentially escalate privileges within the internal network. The attack vector is particularly dangerous because it leverages the trust relationship that exists between users and the VPN system, allowing malicious actors to operate within the legitimate session context while performing unauthorized activities. This vulnerability effectively transforms the VPN from a security boundary into a potential attack vector that can be used to compromise internal systems.
The fundamental design problem highlighted by CVE-2009-2631 aligns with CWE-352, which addresses Cross-Site Request Forgery vulnerabilities, and maps to ATT&CK technique T1071.004 for application layer protocol usage. Organizations must implement comprehensive mitigation strategies including strict domain restrictions, proper content filtering, and network segmentation to prevent this vulnerability from being exploited. Security professionals should consider the broader implications of this design flaw and evaluate whether their current clientless VPN implementations can be trusted to maintain proper security boundaries, as the vulnerability exists at the core architectural level rather than as a simple software bug that can be patched.