CVE-2025-59529

Published Dec 18, 2025

Last updated 3 months ago

CVSS medium 5.5

Overview

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-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.
Source: security-advisories@github.com
NVD status: Analyzed
Products: avahi

Risk scores

CVSS 3.1

Type: Secondary
Base score: 5.5
Impact score: 3.6
Exploitability score: 1.8
Vector string: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity: MEDIUM

Weaknesses

security-advisories@github.com: CWE-400

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:avahi:avahi:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "6481267F-934F-4A0C-9B25-59738E798458",
            "versionEndExcluding": "0.9",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:avahi:avahi:0.9:rc1:*:*:*:*:*:*",
            "matchCriteriaId": "76971590-AEED-4CB1-B7B7-45EA8FD11524",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.

Overview

Risk scores

CVSS 3.1

Weaknesses

Social media

Configurations

Related CVEs

References