CVE-2020-25686

LOW EPSS 91.0%
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 receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the "Birthday Attacks" section of RFC5452. 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
91.0% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 2

CWE-290
CWE-358

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=1890125
    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=1890125
    Issue TrackingPatchThird Party Advisory