CVE-2020-25686
Published: 19 January 2021
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.
Priority
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)
|
|
| trusty |
Needs triage
|
|
| upstream |
Released
(2.83)
|
|
| xenial |
Released
(2.75-1ubuntu0.16.04.7)
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 3.7 |
| Attack vector | Network |
| Attack complexity | High |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | Low |
| Availability impact | None |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |