CVE-2020-25685

 

Published at: - 20-01-2021 05:15

Last modified: - 07-10-2022 04:15

Total changes: - 12

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.

Common Vulnerability Scoring System (CVSS)

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

 

Verification logic

 

Reference

• https://www.jsof-tech.com/disclosures/dnspooq/
• https://bugzilla.redhat.com/show_bug.cgi?id=1889688
• FEDORA-2021-84440e87ba-Mailing List, Third Party Advisory
• GLSA-202101-17-Third Party Advisory
• DSA-4844-Third Party Advisory
• FEDORA-2021-2e4c3d5a9d-Mailing List, Third Party Advisory
• https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61

 

Keywords

NVD

 

CVE-2020-25685

 

CVE

 

Common vulnerabilities & exposures

 

CVSS

 

Common vulnerability scoring system

 

Security

 

Vulnerabilities

 

Exposures