CVE-2006-5461 in Avahi
Summary
by MITRE
Avahi before 0.6.15 does not verify the sender identity of netlink messages to ensure that they come from the kernel instead of another process, which allows local users to spoof network changes to Avahi.
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Analysis
by VulDB Data Team • 04/27/2026
The vulnerability identified as CVE-2006-5461 affects the Avahi service discovery daemon version 0.6.14 and earlier, representing a critical security flaw in network service management. Avahi is a free software implementation of zero-configuration networking that allows services to be discovered automatically on local networks without requiring centralized configuration. This daemon operates by listening for network events and responding to service advertisements, making it a crucial component in modern network environments where devices need to communicate seamlessly without manual configuration.
The technical flaw resides in Avahi's improper validation of netlink message sources, which are kernel-level communication mechanisms used for exchanging network information between kernel space and user space processes. Specifically, the daemon fails to verify that incoming netlink messages originate from the kernel itself rather than from potentially malicious local processes. This validation gap creates a privilege escalation vector where local attackers can craft and send spoofed netlink messages that appear to come from the kernel, thereby tricking Avahi into accepting false network change notifications.
This vulnerability operates at the intersection of several security domains and can be classified under CWE-20, "Improper Input Validation," and more specifically relates to CWE-284, "Improper Access Control." The attack scenario involves a local user with minimal privileges who can exploit this weakness to manipulate Avahi's network state perception. Since Avahi relies on these netlink messages for service discovery and network monitoring, an attacker can potentially cause the daemon to incorrectly announce or remove network services, leading to service disruption or unauthorized network modifications.
The operational impact of this vulnerability extends beyond simple service disruption, as it can enable more sophisticated attacks within the local network environment. Network service discovery is fundamental to many applications and can be leveraged for reconnaissance purposes, where attackers might use the spoofed network changes to identify active services or devices on the network. The attack aligns with techniques described in the MITRE ATT&CK framework under T1068, "Exploitation for Privilege Escalation," and T1566, "Phishing," as local privilege escalation can lead to broader network infiltration. Additionally, this vulnerability can be exploited to perform man-in-the-middle attacks against local network services that depend on Avahi for service discovery.
Mitigation strategies for CVE-2006-5461 primarily focus on updating to Avahi version 0.6.15 or later, which includes proper validation of netlink message sources. System administrators should also implement additional security measures such as restricting local user privileges, monitoring for unusual network service changes, and employing network segmentation to limit the potential impact of such attacks. The vulnerability demonstrates the importance of proper kernel-space communication validation and highlights the need for security-conscious programming practices in network daemons that handle critical system functions. Organizations should also consider implementing intrusion detection systems that can monitor for anomalous netlink message patterns and regularly audit network service discovery configurations to ensure proper security controls are in place.