CVE-2020-25686

Dnsmasq vulnerability

CVSS

3.7

EPSS

4.9%

EPSS pct

91th

Exploited

No known

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.

Affected vendor

Thekelleys

Affected product

Dnsmasq

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Weakness type (CWE)

CWE-358
CWE-290 — Authentication Bypass by Spoofing

Published

2021-01-20

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, high attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to low impact to integrity.

Its EPSS score of 4.9% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 91% of all scored CVEs.

Check your external exposure to CVE-2020-25686

Confirm whether Thekelleys Dnsmasq is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2020-25686.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2020-25686

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