CVE-2024-52616 identifies a vulnerability in the Avahi-daemon, an open-source implementation of the Zeroconf protocol used for local network service discovery and multicast DNS resolution. The flaw arises because Avahi initializes DNS transaction IDs randomly only once during startup. After this initial randomization, the transaction IDs are incremented sequentially for subsequent DNS queries. This predictable sequence significantly reduces the entropy of transaction IDs, which are intended to prevent DNS spoofing by making it difficult for attackers to guess valid IDs. An attacker on the same network or with the ability to intercept DNS queries can exploit this predictability to craft spoofed DNS responses with correct transaction IDs, thereby poisoning DNS caches or redirecting traffic to malicious endpoints. The vulnerability does not require any privileges or user interaction, making it remotely exploitable over the network. The impact is primarily on the integrity of DNS responses, potentially enabling man-in-the-middle attacks or traffic interception. Although no known exploits have been reported in the wild yet, the vulnerability's nature and ease of exploitation make it a credible threat. The CVSS v3.1 base score is 5.3, reflecting medium severity with network attack vector, low attack complexity, no privileges required, and no user interaction needed. The scope is unchanged, and the impact affects integrity but not confidentiality or availability. Avahi is widely used in Linux-based systems and embedded devices for local network service discovery, making this vulnerability relevant to many environments that rely on multicast DNS. The lack of a patch link suggests that fixes may be pending or distributed through vendor updates. Organizations should monitor vendor advisories and apply updates promptly once available.

For European organizations, the vulnerability poses a risk to the integrity of local DNS resolution within internal networks. Successful exploitation can lead to DNS spoofing attacks, enabling attackers to redirect traffic to malicious hosts, intercept sensitive communications, or disrupt network services by poisoning DNS caches. This can facilitate further attacks such as credential theft, malware distribution, or lateral movement within corporate networks. Sectors relying heavily on Linux-based infrastructure and Avahi for service discovery—such as telecommunications, manufacturing, and research institutions—may face increased risk. The impact is heightened in environments with less network segmentation or where multicast DNS traffic is not adequately monitored or filtered. Although confidentiality and availability are not directly impacted, the integrity compromise can undermine trust in network communications and lead to significant operational and reputational damage. The absence of known exploits in the wild provides a window for proactive mitigation, but the medium CVSS score indicates that organizations should not delay remediation efforts.

1. Apply patches or updates from Avahi maintainers or Linux distribution vendors as soon as they become available to ensure transaction IDs are randomized per DNS query rather than incremented sequentially. 2. Implement network segmentation and isolate multicast DNS traffic to trusted network segments to limit exposure to potential attackers. 3. Deploy DNS spoofing detection mechanisms such as monitoring for anomalous DNS transaction ID patterns or unexpected DNS responses within the local network. 4. Use network-level protections like ingress and egress filtering, and employ DNSSEC where possible to validate DNS responses cryptographically, mitigating spoofing risks. 5. Restrict access to multicast DNS services to authorized devices only, using firewall rules or access control lists. 6. Educate network administrators about the vulnerability and encourage regular auditing of DNS traffic and Avahi daemon configurations. 7. Consider disabling Avahi on systems where multicast DNS is not required to reduce the attack surface.