CVE-2008-2326 in Bonjour
Summary
by MITRE
mDNSResponder in the Bonjour Namespace Provider in Apple Bonjour for Windows before 1.0.5 allows attackers to cause a denial of service (NULL pointer dereference and application crash) by resolving a crafted .local domain name that contains a long label.
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Analysis
by VulDB Data Team • 12/28/2025
The vulnerability identified as CVE-2008-2326 affects the mDNSResponder component within Apple Bonjour for Windows version 1.0.4 and earlier. This issue resides in the Bonjour Namespace Provider implementation that handles DNS-based service discovery operations. The flaw manifests when the system processes specially crafted .local domain names containing excessively long labels, leading to a critical null pointer dereference condition that ultimately results in application crash and denial of service. This vulnerability specifically targets the Windows implementation of Bonjour's multicast dns functionality, which is designed to enable zero-configuration networking services on local networks.
The technical root cause of this vulnerability stems from inadequate input validation within the mDNSResponder parsing logic. When processing a maliciously constructed .local domain name with an abnormally long label, the software fails to properly handle the boundary conditions during label parsing operations. This results in a NULL pointer dereference exception that terminates the application process without proper error handling. The vulnerability represents a classic buffer overflow scenario where the system does not validate the length of domain name labels before attempting to process them, creating a condition where memory access violations occur during normal operation. According to CWE classification, this corresponds to CWE-476 which describes NULL Pointer Dereference, a fundamental programming error that leads to application instability and potential system compromise.
The operational impact of this vulnerability extends beyond simple denial of service as it can be exploited by remote attackers to disrupt network services on affected Windows systems. Any device running Bonjour for Windows before version 1.0.5 becomes vulnerable to this attack when it attempts to resolve the malicious domain name, potentially affecting network discovery services, printer sharing, file sharing, and other applications that rely on Bonjour for service discovery. The vulnerability is particularly concerning in enterprise environments where Bonjour services are commonly deployed for seamless device integration and network management. From an attacker perspective, this represents a low-effort, high-impact vector that can be exploited through simple DNS resolution requests, making it suitable for both casual disruption and more sophisticated attack scenarios.
This vulnerability aligns with ATT&CK technique T1499.001 which describes Network Denial of Service attacks, specifically targeting service availability through application crashes. The attack surface includes any Windows system with Bonjour installed that processes DNS queries from untrusted sources. Organizations running affected versions should prioritize immediate patch deployment as the fix involves proper input validation and bounds checking for domain name label lengths. The recommended mitigation strategy includes updating to Bonjour for Windows version 1.0.5 or later, implementing network segmentation to limit exposure, and monitoring for suspicious DNS resolution patterns that might indicate exploitation attempts. Security administrators should also consider disabling Bonjour services on systems where they are not required to reduce the attack surface. The vulnerability demonstrates the importance of robust input validation in network services and highlights how seemingly benign operations like DNS resolution can become attack vectors when proper boundary checks are absent.