Skip to content
Fencer Vulns
medium 4.0

CVE-2021-3448 json

A flaw was found in dnsmasq in versions before 2.85.

published 2021-04-08 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26773

cvss
4.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

A flaw was found in dnsmasq in versions before 2.85. When configured to use a specific server for a given network interface, dnsmasq uses a fixed port while forwarding queries. An attacker on the network, able to find the outgoing port used by dnsmasq, only needs to guess the random transmission ID to forge a reply and get it accepted by dnsmasq. This flaw makes a DNS Cache Poisoning attack much easier. The highest threat from this vulnerability is to data integrity.

Patch / fix

  • thekelleys dnsmasq 2.85
  • dnsmasq Debian 14, Debian 13, Debian 12 2.85-1

debian advisories DEBIAN-CVE-2021-3448

  • dnsmasq Ubuntu 18.04 LTS 2.79-1ubuntu0.4
  • dnsmasq Ubuntu 20.04 LTS 2.80-1.1ubuntu1.4
  • dnsmasq Ubuntu Pro 16.04 LTS 2.79-1ubuntu0.16.04.1+esm1

ubuntu advisories UBUNTU-CVE-2021-3448

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dnsmasq RHEL 8 2.79-19.el8
  • dnsmasq-utils RHEL 8 2.79-19.el8

red hat advisories RHSA-2021:4153

  • dnsmasq SLE Point of Sale 11 SP3 2.78-0.16.17.1
  • dnsmasq SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +10 more 2.78-18.18.1
  • dnsmasq SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 2.78-150000.3.14.1
  • dnsmasq SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +7 more 2.86-7.14.1
  • dnsmasq SLES 11 SP4-LTSS 2.78-0.17.18.1

suse advisories SUSE-SU-2022:14941-1SUSE-SU-2022:14940-1SUSE-SU-2022:1289-1SUSE-SU-2022:1288-1SUSE-SU-2021:3530-1

  • dnsmasq openSUSE Tumbleweed 2.86-1.1
  • dnsmasq openSUSE Leap 15.2 2.86-lp152.7.6.1
  • dnsmasq openSUSE Leap 15.3 2.86-7.14.1

opensuse advisories openSUSE-SU-2024:10721-1openSUSE-SU-2021:1426-1openSUSE-SU-2021:3530-1

  • dnsmasq AlmaLinux 8 2.79-19.el8
  • dnsmasq-utils AlmaLinux 8 2.79-19.el8

almalinux advisories ALSA-2021:4153

  • dnsmasq Rocky Linux 8 2.79-19.el8

rocky linux advisories RLSA-2021:4153

  • dnsmasq Alpine 3.24, Alpine 3.23, Alpine 3.22 +12 more 2.85-r0

alpine advisories ALPINE-CVE-2021-3448

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dnsmasq Arch Linux 2.85-1

arch linux advisories AVG-1703

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3448 updated cvss 4.0

dnsmasq: fixed outgoing port used when --server is used with an interface name

  • Red Hat Enterprise Linux 6 dnsmasq, dnsmasq-utils Red Hat Enterprise Linux 7 dnsmasq, dnsmasq-utils
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) dnsmasq 2.79-19.el8, dnsmasq-utils 2.79-19.el8
    fixed: vendor fix RHSA-2021:4153
  • Red Hat Enterprise Linux 9 dnsmasq, dnsmasq-utils Red Hat OpenStack Platform 10 (Newton) dnsmasq-utils Red Hat OpenStack Platform 13 (Queens) dnsmasq-utils
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
11 mo ago

Exploit prediction

2.28% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=1939368 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
NVD 3.1 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
CNA 3.1 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • n/a dnsmasq

Classification

Weakness
  • CWE-358 Improperly Implemented Security Check for Standard

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.