CVE-2020-25685

LOW EPSS 80.1%
Published Jan 20, 20215y ago · Modified Jun 17, 20262w ago
3.7 CVSS 3.1
Low
Find Similar
Published Jan 20, 2021 5y ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
3.7
Exploitability
2.2
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
80.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-326

Affected Products 9

VendorProductVersionRange
thekelleysdnsmasq* <2.83
fedoraprojectfedora32any
fedoraprojectfedora33any
debiandebian_linux10.0any
aristaeos*≥4.21  –  <4.21.14m
aristaeos*≥4.22  –  <4.22.9m
aristaeos*≥4.23  –  <4.23.7m
aristaeos*≥4.24  –  <4.24.5m
aristaeos*≥4.25  –  <4.25.2f

References 8

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=1889688
    Issue TrackingPatchThird Party Advisory
  • lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
  • lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
  • security.gentoo.org https://security.gentoo.org/glsa/202101-17
    Third Party Advisory
  • arista.com https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61
    Third Party Advisory
  • debian.org https://www.debian.org/security/2021/dsa-4844
    Third Party Advisory
  • jsof-tech.com https://www.jsof-tech.com/disclosures/dnspooq/
    Third Party Advisory
  • kb.cert.org https://www.kb.cert.org/vuls/id/434904

Remediation

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=1889688
    Issue TrackingPatchThird Party Advisory