CVE-2025-59529

Name of the Vulnerable Software and Affected Versions Avahi versions up to and including 0.9-rc2

Description Avahi is a system that enables service discovery on a local network using the mDNS/DNS-SD protocol suite. The simple protocol server does not enforce the documented client limit, accepting an unlimited number of connections. This allows unprivileged local users to exhaust the daemon's memory and file descriptors, leading to a denial of service system-wide for mDNS/DNS-SD. The issue stems from the server work() function unconditionally accepting connections and the client new() function always appending new clients without checking against the CLIENTS MAX limit. Exhausting local file descriptors results in increased system load due to error logging for each connection attempt. Overloading the system prevents glibc calls using nss-mdns plugins from resolving *.local. names and link-local addresses. Tools like avahi-resolve, avahi-resolve-address, and avahi-resolve-host-name, which use the DBus interface, are not directly affected.

Recommendations Versions prior to 0.9-rc2 are affected. At the moment, there is no information about a newer version that contains a fix for this vulnerability.