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CVE

CVE-2020-25686

A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending

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.

LOW · CVSS 3.7 EPSS 0.00549
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  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-290Authentication Bypass by Spoofing
CWE-358Improperly Implemented Security Check for Standard
▤

Affected Products & Versions

8
thekelleys dnsmasq< 2.83
fedoraproject fedoraall versions
debian linuxall versions
arista eos>= 4.21 and < 4.21.14m
arista eos>= 4.22 and < 4.22.9m
arista eos>= 4.23 and < 4.23.7m
arista eos>= 4.24 and < 4.24.5m
arista eos>= 4.25 and < 4.25.2f
▣

Scoring & Timeline

3.7
LOW · CVSS v3.1 · secalert@redhat.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD20 Jan 2021 · 05:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
⚑

Vendor Advisories

24
suse-csafopenSUSE-SU-2024:10721-1
msrcCVE-2020-25686
rhsaRHSA-2021:0401Important
rhsaRHSA-2021:0395Important
suse-csafopenSUSE-SU-2021:0124-1
🔗

References & Sources

8
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://bugzilla.redhat.com/show_bug.cgi?id=1890125Issue TrackingPatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
https://security.gentoo.org/glsa/202101-17Third Party Advisory
https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61Third Party Advisory
https://www.debian.org/security/2021/dsa-4844Third Party Advisory
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