CVE-2025-68276
📋 TL;DR
This vulnerability allows unprivileged local users to crash the Avahi daemon by creating record browsers with the AVAHI_LOOKUP_USE_WIDE_AREA flag set via D-Bus. This affects systems running Avahi 0.9-rc2 and earlier with wide-area discovery disabled. The attack requires local access to the system.
💻 Affected Systems
- Avahi
📦 What is this software?
Avahi by Avahi
Avahi by Avahi
⚠️ Risk & Real-World Impact
Worst Case
Denial of service causing disruption of local network service discovery, potentially affecting applications that rely on Avahi for service discovery.
Likely Case
Local user causes temporary service disruption until Avahi daemon restarts, affecting mDNS/DNS-SD functionality on the local system.
If Mitigated
Minimal impact if Avahi is not critical for system operations or if proper access controls limit local user privileges.
🎯 Exploit Status
Exploitation requires local user access and knowledge of D-Bus API calls to trigger the crash condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after commit ede7048475c5d47d53890e3bc1350dda8e0b3688
Vendor Advisory: https://github.com/avahi/avahi/security/advisories/GHSA-mhf3-865v-g5rc
Restart Required: Yes
Instructions:
1. Update Avahi to a patched version from your distribution's repositories. 2. Restart the avahi-daemon service. 3. Verify the fix by checking the Avahi version.
🔧 Temporary Workarounds
Disable Avahi service
linuxCompletely disable Avahi if not needed for your environment
sudo systemctl stop avahi-daemon
sudo systemctl disable avahi-daemon
Restrict D-Bus access
linuxConfigure D-Bus policies to restrict access to Avahi methods for unprivileged users
🧯 If You Can't Patch
- Monitor for avahi-daemon crashes and implement automatic restart mechanisms
- Implement strict access controls to limit local user accounts on affected systems
🔍 How to Verify
Check if Vulnerable:
Check Avahi version: avahi-daemon --version. If version is 0.9-rc2 or earlier, system is vulnerable.Check Version:
avahi-daemon --versionVerify Fix Applied:
After patching, verify version is newer than 0.9-rc2 and test that record browsers with AVAHI_LOOKUP_USE_WIDE_AREA flag don't crash the daemon.📡 Detection & Monitoring
Log Indicators:
- Avahi daemon crash logs in systemd journal
- Segmentation fault errors in avahi-daemon logs
Network Indicators:
- Loss of mDNS/DNS-SD service announcements on local network
SIEM Query:
process.name:"avahi-daemon" AND event.action:"crashed" OR log.level:"error" AND message:"segmentation fault"