CVE-2020-25685

CVE Details

Release Date:

2021-01-20

Description

A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in forward.c:reply_query(), which is the forwarded query that matches the reply, by only using a weak hash of the query name. Due to the weak hash (CRC32 when dnsmasq is compiled without DNSSEC, SHA-1 when it is) this flaw allows an off-path attacker to find several different domains all having the same hash, substantially reducing the number of attempts they would have to perform to forge a reply and get it accepted by dnsmasq. This is in contrast with RFC5452, which specifies that the query name is one of the attributes of a query that must be used to match a reply. This flaw could be abused to perform a DNS Cache Poisoning attack. 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.

See more information about CVE-2020-25685 from MITRE CVE dictionary and NIST NVD

CVSS v3.0 metrics

NOTE: The following CVSS v3.0 metrics and score provided are preliminary and subject to review.

Base Score:	3.7	Base Metrics:	AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Access Vector:	Network	Attack Complexity:	High
Privileges Required:	None	User Interaction:	None
Scope:	Unchanged	Confidentiality Impact:	None
Integrity Impact:	Low	Availability Impact:	None

Errata information

Platform	Errata	Release Date
Oracle Linux version 7 (dnsmasq)	ELSA-2021-0153	2021-01-19
Oracle Linux version 8 (dnsmasq)	ELSA-2021-0150	2021-01-20

This page is generated automatically and has not been checked for errors or omissions. For clarification or corrections please contact the Oracle Linux ULN team