CVE-2002-0068 in Squid
Summary
by MITRE
Squid 2.4 STABLE3 and earlier allows remote attackers to cause a denial of service (core dump) and possibly execute arbitrary code with an ftp:// URL with a larger number of special characters, which exceed the buffer when Squid URL-escapes the characters.
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Analysis
by VulDB Data Team • 09/23/2025
The vulnerability described in CVE-2002-0068 represents a critical buffer overflow condition within the Squid web proxy software version 2.4 STABLE3 and earlier. This flaw specifically manifests when processing ftp:// URLs containing an excessive number of special characters that exceed the allocated buffer space during URL-escaping operations. The issue stems from insufficient input validation and boundary checking within Squid's URL parsing and processing functions, creating a scenario where maliciously crafted URLs can trigger unpredictable behavior in the proxy service.
The technical implementation of this vulnerability involves Squid's handling of URL-escaping mechanisms for ftp protocol addresses. When the proxy encounters an ftp:// URL with an unusually high density of special characters, the internal buffer allocated for processing these escaped sequences becomes insufficient to accommodate the expanded character set. This buffer overflow condition can result in memory corruption that manifests as a core dump, effectively crashing the Squid service and causing a denial of service. The vulnerability's severity escalates when considering that the overflow may potentially allow for arbitrary code execution, as memory corruption can be exploited to manipulate program execution flow.
The operational impact of CVE-2002-0068 extends beyond simple service disruption to potentially enable remote code execution attacks against systems running vulnerable Squid versions. Organizations relying on Squid as their primary web proxy face significant risk when exposed to this vulnerability, as attackers can craft malicious URLs that, when processed by the proxy, either crash the service or provide a pathway for unauthorized code execution. This vulnerability particularly affects enterprise environments where Squid serves as a critical component for web filtering, caching, and proxy services, potentially compromising entire network infrastructures when exploited.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation that enables memory corruption attacks. The attack vector maps to ATT&CK technique T1203, specifically involving the exploitation of software vulnerabilities to gain unauthorized access or execute malicious code. Organizations should implement immediate mitigations including upgrading to patched versions of Squid, implementing URL filtering rules to block suspicious character patterns, and deploying network monitoring to detect potential exploitation attempts. Additionally, the vulnerability highlights the importance of proper input sanitization and boundary checking in proxy and web application software, emphasizing the need for defensive programming practices that prevent buffer overflow conditions through robust validation mechanisms and memory management protocols.