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low 3.7

CVE-2020-25686 json

A flaw was found in dnsmasq before version 2.83.

published 5y ago modified 4mo ago also EUVD-2020-18348

cvss
3.7
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
5.5%
EPSS 5.5% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

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.

Patch / fix

  • thekelleys dnsmasq 2.83
  • arista eos 4.21.14m, 4.22.9m, 4.23.7m, 4.24.5m, 4.25.2f
  • dnsmasq Debian 14, Debian 13, Debian 12 2.83-1

debian advisories DEBIAN-CVE-2020-25686

  • dnsmasq Ubuntu 16.04 LTS 2.75-1ubuntu0.16.04.7
  • dnsmasq Ubuntu 18.04 LTS 2.79-1ubuntu0.2
  • dnsmasq Ubuntu 20.04 LTS 2.80-1.1ubuntu1.2

ubuntu advisories UBUNTU-CVE-2020-25686

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

  • redhat-virtualization-host rhev hypervisor 4.4 4.4.4-20210201.0.el8_3
  • redhat-virtualization-host-image-update rhev hypervisor 4.4 4.4.4-20210201.0.el8_3
  • redhat-virtualization-host RHEL 7 4.3.13-20210127.0.el7_9
  • redhat-virtualization-host-image-update RHEL 7 4.3.13-20210127.0.el7_9
  • dnsmasq RHEL 8 2.79-13.el8_3.1
  • dnsmasq-utils RHEL 8 2.79-13.el8_3.1
  • dnsmasq RHEL 7 2.76-16.el7_9.1
  • dnsmasq-utils RHEL 7 2.76-16.el7_9.1

red hat advisories RHSA-2021:0401RHSA-2021:0395RHSA-2021:0240RHSA-2021:0245RHSA-2021:0150RHSA-2021:0155

  • dnsmasq SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +14 more 2.78-18.15.1
  • dnsmasq SLE Point of Sale 11 SP3 2.78-0.16.14.1
  • dnsmasq SLE Module for Basesystem 15 SP2, SLE Module for Basesystem 15 SP1 2.78-7.6.1
  • dnsmasq SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 2.78-3.11.1
  • dnsmasq SLES 11 SP4-LTSS 2.78-0.17.15.1

suse advisories SUSE-SU-2021:0166-1SUSE-SU-2021:14604-1SUSE-SU-2021:14603-1SUSE-SU-2021:0163-1SUSE-SU-2021:0162-1

  • dnsmasq openSUSE Tumbleweed 2.86-1.1
  • dnsmasq openSUSE Leap 15.1 2.78-lp151.5.6.1
  • dnsmasq openSUSE Leap 15.2 2.78-lp152.7.3.1

opensuse advisories openSUSE-SU-2024:10721-1openSUSE-SU-2021:0129-1openSUSE-SU-2021:0124-1

  • dnsmasq Alpine 3.24, Alpine 3.23, Alpine 3.22 +12 more 2.83-r0

alpine advisories ALPINE-CVE-2020-25686

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 2.83-1

arch linux advisories AVG-1470

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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-2020-25686 updated cvss 4.0

dnsmasq: multiple queries forwarded for the same name makes forging replies easier for an off-path attacker

  • Red Hat Enterprise Linux 5 dnsmasq Red Hat Enterprise Linux 6 dnsmasq, dnsmasq-utils
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) dnsmasq 2.79-13.el8_3.1, dnsmasq-utils 2.79-13.el8_3.1
    fixed: vendor fix RHSA-2021:0150
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) dnsmasq 2.79-6.el8_1.1, dnsmasq-utils 2.79-6.el8_1.1
    fixed: vendor fix RHSA-2021:0152
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) dnsmasq 2.79-11.el8_2.2, dnsmasq-utils 2.79-11.el8_2.2
    fixed: vendor fix RHSA-2021:0151
  • Red Hat Enterprise Linux Client (v. 7) dnsmasq 2.76-16.el7_9.1 Red Hat Enterprise Linux Client Optional (v. 7) dnsmasq-utils 2.76-16.el7_9.1
    fixed: vendor fix RHSA-2021:0153
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.6) dnsmasq 2.76-7.el7_6.2
    fixed: vendor fix RHSA-2021:0155
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.7) dnsmasq 2.76-10.el7_7.2
    fixed: vendor fix RHSA-2021:0154
  • Red Hat Enterprise Linux ComputeNode Optional (v. 7) dnsmasq-utils 2.76-16.el7_9.1
    fixed: vendor fix RHSA-2021:0153
show 21 more
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.6) dnsmasq-utils 2.76-7.el7_6.2
    fixed: vendor fix RHSA-2021:0155
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.7) dnsmasq-utils 2.76-10.el7_7.2
    fixed: vendor fix RHSA-2021:0154
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) dnsmasq 2.76-7.el7_6.2 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) dnsmasq-utils 2.76-7.el7_6.2
    fixed: vendor fix RHSA-2021:0155
  • Red Hat Enterprise Linux Server (v. 7) dnsmasq 2.76-16.el7_9.1
    fixed: vendor fix RHSA-2021:0153
  • Red Hat Enterprise Linux Server AUS (v. 7.2) dnsmasq 2.66-14.el7_2.3
    fixed: vendor fix RHSA-2021:0240
  • Red Hat Enterprise Linux Server AUS (v. 7.3) dnsmasq 2.66-21.el7_3.3
    fixed: vendor fix RHSA-2021:0245
  • Red Hat Enterprise Linux Server AUS (v. 7.4) dnsmasq 2.76-2.el7_4.3 Red Hat Enterprise Linux Server E4S (v. 7.4) dnsmasq 2.76-2.el7_4.3
    fixed: vendor fix RHSA-2021:0156
  • Red Hat Enterprise Linux Server EUS (v. 7.6) dnsmasq 2.76-7.el7_6.2
    fixed: vendor fix RHSA-2021:0155
  • Red Hat Enterprise Linux Server EUS (v. 7.7) dnsmasq 2.76-10.el7_7.2
    fixed: vendor fix RHSA-2021:0154
  • Red Hat Enterprise Linux Server Optional (v. 7) dnsmasq-utils 2.76-16.el7_9.1
    fixed: vendor fix RHSA-2021:0153
  • Red Hat Enterprise Linux Server Optional AUS (v. 7.2) dnsmasq-utils 2.66-14.el7_2.3
    fixed: vendor fix RHSA-2021:0240
  • Red Hat Enterprise Linux Server Optional AUS (v. 7.3) dnsmasq-utils 2.66-21.el7_3.3
    fixed: vendor fix RHSA-2021:0245
  • Red Hat Enterprise Linux Server Optional AUS (v. 7.4) dnsmasq-utils 2.76-2.el7_4.3 Red Hat Enterprise Linux Server Optional E4S (v. 7.4) dnsmasq-utils 2.76-2.el7_4.3
    fixed: vendor fix RHSA-2021:0156
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.6) dnsmasq-utils 2.76-7.el7_6.2
    fixed: vendor fix RHSA-2021:0155
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.7) dnsmasq-utils 2.76-10.el7_7.2
    fixed: vendor fix RHSA-2021:0154
  • Red Hat Enterprise Linux Server Optional TUS (v. 7.4) dnsmasq-utils 2.76-2.el7_4.3 Red Hat Enterprise Linux Server TUS (v. 7.4) dnsmasq 2.76-2.el7_4.3
    fixed: vendor fix RHSA-2021:0156
  • Red Hat Enterprise Linux Workstation (v. 7) dnsmasq 2.76-16.el7_9.1 Red Hat Enterprise Linux Workstation Optional (v. 7) dnsmasq-utils 2.76-16.el7_9.1
    fixed: vendor fix RHSA-2021:0153
  • Red Hat Virtualization 4 Hypervisor for RHEL 7 redhat-virtualization-host 4.3.13-20210127.0.el7_9, redhat-virtualization-host-image-update 4.3.13-20210127.0.el7_9
    fixed: vendor fix RHSA-2021:0395
  • Red Hat Virtualization 4 Hypervisor for RHEL 8 redhat-virtualization-host 4.4.4-20210201.0.el8_3, redhat-virtualization-host-image-update 4.4.4-20210201.0.el8_3
    fixed: vendor fix RHSA-2021:0401
  • Red Hat RHEL 7-based RHEV-H for RHEV 4 (build requirements) redhat-virtualization-host 4.3.13-20210127.0.el7_9, redhat-virtualization-host-image-update 4.3.13-20210127.0.el7_9
    fixed: vendor fix RHSA-2021:0395
  • Red Hat Enterprise Linux 9 dnsmasq, dnsmasq-utils Red Hat OpenStack Platform 10 (Newton) dnsmasq-utils Red Hat OpenStack Platform 13 (Queens) dnsmasq-utils Red Hat Virtualization 4 Hypervisor for RHEL 8 sssd 2.3.0-9.el8, sssd-ad 2.3.0-9.el8, sssd-ipa 2.3.0-9.el8, sssd-kcm 2.3.0-9.el8, samba 4.12.3-12.el8.3, sssd-dbus 2.3.0-9.el8, +25 more Red Hat Virtualization 4 Management Agent for RHEL 7 Hosts vdsm 4.30.51-1.el7ev, vdsm-api 4.30.51-1.el7ev, vdsm-http 4.30.51-1.el7ev, vdsm-client 4.30.51-1.el7ev, vdsm-common 4.30.51-1.el7ev, vdsm-python 4.30.51-1.el7ev, +17 more
    not affected: vulnerable code not present

2 more not affected in the full advisory

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 ICSA-21-019-01 updated cvss 4.0

dnsmasq by Simon Kelley (Update A)

  • Siemens RUGGEDCOM RM1224 <V6.4 Siemens SCALANCE M-800 <V6.4 Siemens SCALANCE S615 <V6.4
    affected: fixed in V6.4, mitigation support.industry.siemens.com
  • Siemens SCALANCE SC-600 <V2.1.3
    affected: fixed in V2.1.3, mitigation support.industry.siemens.com
  • Siemens SCALANCE W1750D
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

5.47% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/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
  • CWE-290 Authentication Bypass by Spoofing

References

Sources

Fencer Intel 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.