CVE-2020-25685

Severity CVSS v4.0:

Pending analysis

Type:

CWE-326 Inadequate Encryption Strength

Publication date:

20/01/2021

Last modified:

07/11/2023

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.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 3.70 LOW
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): High
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): Low
Availability (A): None

Base Score 3.x

3.70

Severity 3.x

LOW

Vector 2.0

AV:N/AC:M/Au:N/C:N/I:P/A:N CVSS v2.0 Severity and Metrics:

Base Score: 4.30 MEDIUM
Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Medium
Authentication (Au): None
Confidentiality (C): None
Integrity (I): Physical
Availability (A): None

Base Score 2.0

4.30

Severity 2.0

MEDIUM

Vulnerable products and versions

CPE	From	Up to
cpe:2.3:a:thekelleys:dnsmasq::::::::		2.83 (excluding)
cpe:2.3:o:fedoraproject:fedora:32:::::::*
cpe:2.3:o:fedoraproject:fedora:33:::::::*
cpe:2.3:o:debian:debian_linux:10.0:::::::*
cpe:2.3:o:arista:eos::::::::	4.21 (including)	4.21.14m (excluding)
cpe:2.3:o:arista:eos::::::::	4.22 (including)	4.22.9m (excluding)
cpe:2.3:o:arista:eos::::::::	4.23 (including)	4.23.7m (excluding)
cpe:2.3:o:arista:eos::::::::	4.24 (including)	4.24.5m (excluding)
cpe:2.3:o:arista:eos::::::::	4.25 (including)	4.25.2f (excluding)

To consult the complete list of CPE names with products and versions, see this page

CVE-2020-25685

Description

Impact

Vulnerable products and versions

References to Advisories, Solutions, and Tools