CVE-2023-38470 in avahi
Summary
by MITRE • 11/02/2023
A vulnerability was found in Avahi. A reachable assertion exists in the avahi_escape_label() function.
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Analysis
by VulDB Data Team • 05/24/2026
The vulnerability in Avahi represents a critical assertion failure within the avahi_escape_label() function that can be triggered through reachable code paths. This issue stems from insufficient input validation and error handling mechanisms within the service discovery daemon that is widely deployed across linux systems for multicast dns service discovery. The assertion failure occurs when processing malformed or unexpected input data during label escaping operations, which are fundamental components in dns label formatting and service name handling. This vulnerability exists in the core networking infrastructure component that enables zero-configuration networking capabilities, making it a prime target for exploitation in network-based attack scenarios.
The technical flaw manifests as an assertion check that fails when the avahi_escape_label() function encounters input data that violates expected formatting constraints. This function is responsible for properly escaping special characters in dns labels according to rfc standards, but lacks adequate defensive programming measures to handle edge cases or malicious input. The assertion failure typically results in process termination or unexpected behavior that can be leveraged by attackers to cause denial of service conditions or potentially escalate privileges depending on the execution context. This type of vulnerability falls under the category of assertion failure or defensive programming error that can be classified as cwe-617, which specifically addresses reachable assertions that can be exploited by attackers to disrupt service availability.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire network discovery infrastructure on affected systems. When exploited, the assertion failure can cause avahi-daemon processes to crash repeatedly, leading to complete loss of multicast dns functionality and service discovery capabilities within the local network segment. This affects not only the immediate system but also other network services that depend on avahi for device and service discovery, including printer sharing, file sharing, and various network management functions. The vulnerability is particularly concerning in enterprise environments where avahi is extensively used for automatic service detection and network configuration management, as it can systematically disable critical network infrastructure components.
Mitigation strategies for this vulnerability require immediate patching of affected avahi versions to address the assertion handling issue in avahi_escape_label() function. System administrators should prioritize deployment of updated avahi packages from their respective distribution vendors to ensure proper input validation and error handling. Additionally, network segmentation and access controls should be implemented to limit exposure of avahi services to untrusted networks or users who could potentially exploit the assertion failure. Monitoring should be enhanced to detect process crashes or restart patterns that could indicate exploitation attempts, while network-based intrusion detection systems should be configured to alert on unusual service discovery traffic patterns. The vulnerability demonstrates the importance of defensive programming practices and proper error handling in network services, aligning with attack technique t1489 which involves denial of service through service interruption, and highlights the need for robust input validation mechanisms as recommended in the software security best practices framework.