CVE-2002-0069 in Squid
Summary
by MITRE
Memory leak in SNMP in Squid 2.4 STABLE3 and earlier allows remote attackers to cause a denial of service.
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Analysis
by VulDB Data Team • 09/23/2025
The vulnerability identified as CVE-2002-0069 represents a critical memory leak flaw within the Simple Network Management Protocol implementation of Squid web proxy software versions 2.4 STABLE3 and earlier. This issue resides in the network management subsystem that processes SNMP requests, creating a condition where allocated memory is not properly released during normal operation. The flaw specifically manifests when the SNMP module handles certain malformed or crafted requests, leading to progressive memory consumption that eventually exhausts available system resources. This memory management deficiency stems from improper resource cleanup routines within the proxy server's network monitoring capabilities, making it particularly dangerous in production environments where continuous operation is expected.
The technical exploitation of this vulnerability occurs when remote attackers send specially crafted SNMP packets to the Squid proxy server, triggering the memory leak condition. The flaw operates at the application layer within the proxy server's SNMP handling code, where memory allocation occurs for processing incoming management requests but subsequent deallocation fails to execute properly. This creates a gradual accumulation of unused memory segments that cannot be reclaimed by the system's memory manager, effectively consuming system resources over time. The vulnerability is classified under CWE-401 as a failure to release memory resources, representing a classic memory leak scenario that can be systematically exploited through network-based attacks.
The operational impact of CVE-2002-0069 extends beyond simple resource exhaustion, as it enables remote attackers to perform denial of service attacks against Squid proxy servers. When the memory leak reaches critical levels, the affected proxy server becomes unresponsive to legitimate requests, effectively rendering the service unavailable to authorized users. This vulnerability particularly affects organizations relying on Squid as a caching proxy or content filtering solution, where proxy server availability is crucial for network operations. The attack can be executed with minimal resources and technical expertise, making it a significant threat to network infrastructure availability. The vulnerability also impacts the broader network ecosystem as proxy servers often serve as critical components in enterprise network architectures, potentially affecting multiple downstream services.
Mitigation strategies for this vulnerability require immediate patching of affected Squid installations to version 2.4 STABLE4 or later, which contains the necessary memory management fixes. Network administrators should implement monitoring solutions to detect unusual memory consumption patterns that may indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service attacks, specifically targeting application layer resources. Additionally, organizations should consider implementing network access controls to restrict SNMP traffic to trusted management systems only, reducing the attack surface. System hardening measures including memory watchdog processes and automated restart procedures can provide additional protection layers. The fix addresses the root cause by implementing proper memory deallocation routines in the SNMP processing code, ensuring that all allocated resources are correctly released regardless of request processing outcomes.