{"id":"CVE-2025-59529","revision":"85f16dfbf0684f2ebbbad30017f617a5","records":[{"revision":"85f16dfbf0684f2ebbbad30017f617a5","observedAt":"2026-10-23T20:48:20.645+00:00","statement":{"source":"cve-program","id":"CVE-2025-59529","aliases":[],"title":"Avahi: simple protocol server ignores accepts unlimited connections and logs failures without limit","description":"Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. In versions up to and including 0.9-rc5, the simple protocol server ignores the documented client limit and accepts unlimited connections, allowing for easy local DoS. Although `CLIENTS_MAX` is defined, `server_work()` unconditionally `accept()`s and `client_new()` always appends the new client and increments `n_clients`. There is no check against the limit. When client cannot be accepted as a result of maximal socket number of avahi-daemon, it logs unconditionally error per each connection. Unprivileged local users can exhaust daemon memory and file descriptors, causing a denial of service system-wide for mDNS/DNS-SD. Exhausting local file descriptors causes increased system load caused by logging errors of each of request. Overloading prevents glibc calls using nss-mdns plugins to resolve `*.local.` names and link-local addresses. As of time of publication, no known patched versions are available, but a candidate fix is available in pull request 808, and some workarounds are available. Simple clients are offered for nss-mdns package functionality. It is not possible to disable the unix socket `/run/avahi-daemon/socket`, but resolution requests received via DBus are not affected directly. Tools avahi-resolve, avahi-resolve-address and avahi-resolve-host-name are not affected, they use DBus interface. It is possible to change permissions of unix socket after avahi-daemon is started. But avahi-daemon does not provide any configuration for it. Additional access restrictions like SELinux can also prevent unwanted tools to access the socket and keep resolution working for trusted users.","state":0,"publishedAt":"2025-12-18T20:25:31.499+00:00","modifiedAt":"2026-10-23T19:33:17.866+00:00","affected":[{"ecosystem":"Vendor product","name":"avahi","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"avahi\",\n                    \"product\": \"avahi\",\n                    \"versions\": [\n                        {\n                            \"version\": \"<= 0.9-rc5\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5,"severity":"MEDIUM"}],"references":["https://github.com/avahi/avahi/security/advisories/GHSA-73wf-3xmj-x82q","https://github.com/avahi/avahi/pull/808","https://github.com/avahi/avahi/pull/975","https://zeropath.com/blog/avahi-simple-protocol-server-dos-cve-2025-59529"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-59529","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-59529","identifiers":["CVE-2025-59529"]},"retained":false,"historicalAffected":[]}],"coverage":[]}