CVE-2009-2673 in JRE
Summary
by MITRE
The proxy mechanism implementation in Sun Java Runtime Environment (JRE) in JDK and JRE 6 before Update 15, and JDK and JRE 5.0 before Update 20, allows remote attackers to bypass intended access restrictions and connect to arbitrary sites via unspecified vectors, related to a declaration that lacks the final keyword.
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Analysis
by VulDB Data Team • 05/14/2025
The vulnerability identified as CVE-2009-2673 represents a critical security flaw in the Java Runtime Environment's proxy mechanism implementation. This weakness affects specific versions of Java Development Kit and Runtime Environment including JDK/JRE 6 before Update 15 and JDK/JRE 5.0 before Update 20. The vulnerability stems from an insufficient implementation of proxy access controls that allows malicious actors to circumvent intended network restrictions. The flaw specifically relates to a declaration that lacks the final keyword, which creates an exploitable condition in the proxy handling logic. This vulnerability falls under the broader category of access control bypass issues and can be categorized under CWE-284 Access Control Bypass. The proxy mechanism in question is designed to control network connections and restrict access to specific resources, but due to the missing final keyword declaration, attackers can manipulate the proxy behavior to establish connections to unauthorized destinations.
The technical implementation flaw occurs within the Java security model where proxy configurations should enforce strict access controls but fail to do so properly. When a declaration lacks the final keyword in the proxy mechanism implementation, it creates a situation where the proxy settings can be overridden or modified by external inputs. This allows attackers to inject malicious proxy configurations that redirect network traffic to arbitrary destinations. The unspecified vectors mentioned in the description suggest that multiple attack paths exist through which an attacker can exploit this weakness, potentially including web-based attacks, applet-based exploitation, or other Java-based network interactions. The vulnerability demonstrates a fundamental flaw in the Java security architecture where the proxy configuration mechanism does not properly validate or enforce access restrictions, creating a pathway for unauthorized network access.
The operational impact of CVE-2009-2673 is significant for organizations running affected Java versions, as it enables remote attackers to bypass network security controls and access restricted resources. Attackers can potentially redirect traffic through compromised proxy servers to access internal networks, exfiltrate sensitive data, or establish command and control connections. This vulnerability can be particularly dangerous in enterprise environments where Java applets or applications are used to access internal resources, as it allows attackers to circumvent firewalls and network segmentation policies. The attack surface expands when considering that Java applets are often executed in web browsers, making this vulnerability exploitable through web-based attacks. The weakness can be leveraged in conjunction with other attack vectors as outlined in the MITRE ATT&CK framework under techniques related to proxy usage and network infiltration. Organizations may experience unauthorized access to internal systems, data breaches, and potential lateral movement within their networks.
Mitigation strategies for CVE-2009-2673 primarily involve updating to patched versions of the Java Runtime Environment. Oracle released updates for JDK and JRE 6 Update 15 and JDK/JRE 5.0 Update 20 that address this specific vulnerability by properly implementing the final keyword in the proxy declaration. System administrators should prioritize patching affected systems and ensure that all Java installations are updated to versions that contain the security fix. Additional mitigations include implementing network-level restrictions such as firewall rules that limit outbound connections from Java applications, disabling unnecessary proxy configurations, and monitoring network traffic for suspicious proxy behavior. Organizations should also consider implementing application whitelisting policies to restrict which Java applications can establish network connections and use proxy mechanisms. The vulnerability highlights the importance of proper access control implementation in security-critical components and reinforces the need for thorough code review processes that ensure security-sensitive declarations are properly protected with appropriate access modifiers. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues in other Java-based applications and components.