CVE-2017-6519: Critical severity Avahi Avahi vulnerability
avahi-daemon in Avahi through 0.6.32 and 0.7 inadvertently responds to IPv6 unicast queries with source addresses that are not on-link, which allows remote attackers to cause a denial of service (traffic amplification) and may cause information leakage by obtaining potentially sensitive information from the responding device via port-5353 UDP packets. NOTE: this may overlap CVE-2015-2809.
Other sources
It was found that avahi responds to unicast queries coming from outside of local network which may cause an information leak, such as disclosing the device type/model that responds to the request or the operating system. The mDNS response may also be used to amplify denial of service attacks against other networks as the response size is greater than the size of request.
External References:
https://www.kb.cert.org/vuls/id/550620
— Red Hat
Affected Software
Remediation
Patch Available
Mitigation
Event History
Frequently Asked Questions
What is the severity of CVE-2017-6519?
CVE-2017-6519 is rated as a denial of service vulnerability that can lead to traffic amplification.
How do I fix CVE-2017-6519?
To fix CVE-2017-6519, upgrade the Avahi package to version 0.8 or later.
Which versions of Avahi are affected by CVE-2017-6519?
Avahi versions up to and including 0.6.32 and 0.7 are affected by CVE-2017-6519.
Can CVE-2017-6519 lead to information leakage?
Yes, CVE-2017-6519 may allow remote attackers to obtain potentially sensitive information.
Is there a workaround for CVE-2017-6519 if I cannot upgrade?
A workaround for CVE-2017-6519 is to restrict access to the Avahi service to only trusted networks.