{"id":"CVE-2025-59529","title":"Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite","summary":"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-rc2, the simple protocol server ignores the documented client limit and accepts unlimited co…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-400"],"vendor":"avahi","product":"avahi","affected":["avahi < 0.9","avahi = 0.9"],"patched":["avahi 0.9"],"published":"2025-12-18","updated":"2026-10-13","sourceUpdated":"2026-10-13T11:10:00.203","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-59529","references":[{"url":"https://github.com/avahi/avahi/pull/808","label":"security-advisories@github.com"},{"url":"https://github.com/avahi/avahi/security/advisories/GHSA-73wf-3xmj-x82q","label":"security-advisories@github.com"},{"url":"https://zeropath.com/blog/avahi-simple-protocol-server-dos-cve-2025-59529","label":"security-advisories@github.com"},{"url":"http://www.openwall.com/lists/oss-security/2025/12/19/1","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00179,"epssPercentile":0.06854,"ingestedAt":"2026-10-13T11:23:51.140Z","slug":"CVE-2025-59529","body":"## Overview\n\nAvahi 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-rc2, 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.\n\n## Affected\n\n- `avahi < 0.9`\n- `avahi = 0.9`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `avahi 0.9`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}