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CVE-2020-25685

LOW
3.7
CVSS Score
Published: January 20, 2021 at 12:00 AM UTC
Updated: June 17, 2026 at 03:07 AM UTC
4 products affected across 4 vendorsDebian LinuxFedoraEos

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Severity
LOW3.7
Exploit prediction
EPSS 2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Eos· Arista
95%
4.21 ≤ v < 4.21.14m4.22 ≤ v < 4.22.9m4.23 ≤ v < 4.23.7m4.24 ≤ v < 4.24.5m4.25 ≤ v < 4.25.2f
Affected range stops below 4.21.14m, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.22.9m, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.23.7m, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.24.5m, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.25.2f, so it looks safe — our inference, not a vendor statement
Debian Linux· Debiandrupal
95%
10.0
Fedora· Fedora Projectrpm
95%
3233
Dnsmasq· Thekelleys
95%
v < 2.832.83
Affected range stops below 2.83, so it looks safe — our inference, not a vendor statement

References (8)

Issue TrackingPatchThird Party Advisory
Source: [email protected]
https://bugzilla.redhat.com/show_bug.cgi?id=1889688
Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
Vendor Advisoryx_refsource_GENTOOThird Party Advisory
Source: [email protected]
https://security.gentoo.org/glsa/202101-17
x_refsource_MISCThird Party Advisory
Source: [email protected]
https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61
Vendor Advisoryx_refsource_DEBIANThird Party Advisory
Source: [email protected]
https://www.debian.org/security/2021/dsa-4844
x_refsource_MISCThird Party Advisory
Source: [email protected]
https://www.jsof-tech.com/disclosures/dnspooq/
Source: af854a3a-2127-422b-91ae-364da2661108
https://www.kb.cert.org/vuls/id/434904

CVSS

3.7LOW[email protected]
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-326

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