CVE-2000-0511 in CUPS
Summary
by MITRE
CUPS (Common Unix Printing System) 1.04 and earlier allows remote attackers to cause a denial of service via a CGI POST request.
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Analysis
by VulDB Data Team • 04/05/2019
The vulnerability identified as CVE-2000-0511 affects the Common Unix Printing System version 1.04 and earlier implementations, representing a critical denial of service weakness that can be exploited remotely through specially crafted CGI POST requests. This flaw resides within the printing system's handling of web-based requests, specifically targeting the web interface component that processes incoming data through the Common Gateway Interface. The issue stems from inadequate input validation and error handling mechanisms within the CUPS web server module, which fails to properly sanitize or reject malformed POST data sent through the CGI interface.
The technical implementation of this vulnerability exploits the insufficient boundary checking and memory management within the CUPS web processing subsystem. When a remote attacker submits a malformed CGI POST request containing oversized or malformed data payloads, the system's web server component becomes overwhelmed with processing requests that trigger buffer overflows or memory corruption conditions. This occurs because the CUPS implementation lacks proper input length validation and does not enforce reasonable limits on the size of data that can be submitted through the CGI interface. The flaw manifests as the web server process becoming unresponsive or crashing entirely, leading to complete service disruption for legitimate users attempting to access the printing system through the web interface.
From an operational perspective, this vulnerability presents significant risk to organizations relying on CUPS for printing services, particularly those with internet-facing printing servers or web-based print management interfaces. The remote exploitation capability means that attackers can compromise system availability without requiring physical access or local credentials, making it particularly dangerous in enterprise environments where printing services are critical for business operations. The denial of service impact extends beyond simple service interruption, as it can affect business continuity and may be used as part of larger attack campaigns targeting network infrastructure. Organizations with multiple CUPS instances or those using the web interface for print job submission, status monitoring, or administrative functions face the highest risk of operational disruption.
The vulnerability aligns with CWE-122, which describes improper restriction of operations within a limited error handling scope, and can be categorized under ATT&CK technique T1499.004 for network denial of service attacks. Mitigation strategies should include immediate patching to CUPS version 1.1.0 or later, which contains the necessary fixes for input validation and memory handling. Network-level protections such as implementing web application firewalls, rate limiting for CGI requests, and access controls restricting web interface access to trusted networks should be deployed. Additionally, system administrators should consider disabling the web interface if not required, implementing proper monitoring for unusual request patterns, and maintaining regular security updates for all system components. The fix typically involves strengthening input validation routines and implementing proper memory management practices to prevent buffer overflow conditions during CGI request processing, ensuring that all user-supplied data is properly validated before being processed by the web server component.