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CVE-2020-25682

Published: 19 January 2021

A flaw was found in dnsmasq before 2.83. A buffer overflow vulnerability was discovered in the way dnsmasq extract names from DNS packets before validating them with DNSSEC data. An attacker on the network, who can create valid DNS replies, could use this flaw to cause an overflow with arbitrary data in a heap-allocated memory, possibly executing code on the machine. The flaw is in the rfc1035.c:extract_name() function, which writes data to the memory pointed by name assuming MAXDNAME*2 bytes are available in the buffer. However, in some code execution paths, it is possible extract_name() gets passed an offset from the base buffer, thus reducing, in practice, the number of available bytes that can be written in the buffer. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Priority

Medium

Cvss 3 Severity Score

8.1

Score breakdown

Status

Package Release Status
dnsmasq
Launchpad, Ubuntu, Debian
bionic
Released (2.79-1ubuntu0.2)
focal
Released (2.80-1.1ubuntu1.2)
groovy
Released (2.82-1ubuntu1.1)
hirsute
Released (2.82-1ubuntu2)
impish
Released (2.82-1ubuntu2)
jammy
Released (2.82-1ubuntu2)
kinetic
Released (2.82-1ubuntu2)
lunar
Released (2.82-1ubuntu2)
mantic
Released (2.82-1ubuntu2)
noble
Released (2.82-1ubuntu2)
trusty Needs triage

upstream
Released (2.83)
xenial
Released (2.75-1ubuntu0.16.04.7)

Severity score breakdown

Parameter Value
Base score 8.1
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H