CVE-2020-25686: Medium severity dnsmasq vulnerability
A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the "Birthday Attacks" section of RFC5452. If chained with CVE-2020-25684, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.
Other sources
When receiving a query, dnsmasq does not check if there is already a pending request for the same name and it forwards a new request for it. By default a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. An attacker on the network can abuse this issue to substantially reduce the number of attempts he would have to perform to forge a reply and get it accepted by dnsmasq. This is mentioned in the "Birthday Attacks" section of RFC5452.
— Red Hat
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is CVE-2020-25686?
CVE-2020-25686 refers to a flaw found in dnsmasq before version 2.83 that allows multiple queries for the same name to be forwarded.
What is the severity of CVE-2020-25686?
The severity of CVE-2020-25686 is medium, with a CVSS score of 3.7.
Which software versions are affected by CVE-2020-25686?
Versions 2.80-1+deb10u1, 2.85-1, and 2.89-1 of dnsmasq are affected by CVE-2020-25686.
How can I fix CVE-2020-25686?
To fix CVE-2020-25686, update dnsmasq to version 2.83 or higher.
Can Arista EOS be affected by CVE-2020-25686?
Yes, Arista EOS versions between 4.21 and 4.25 can be affected by CVE-2020-25686.