CVE-2020-25684

A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

Published: 2021-01-20 Last update: 2025-11-04 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-25684 is rated Low Risk (32.2/100): CVSS Low severity, with medium exploitation likelihood (EPSS 0.27%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-25684

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.52% 0.27% -0.25%
2 2025-11-18 0.27% 0.52% +0.25%
3 2025-10-29 — 0.27% —

Full EPSS history (23 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-25684

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.7 3.1 LOW
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 1.4 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2020-25684

OS Trackers for CVE-2020-25684

vendor priority summary link
alpine — CVE-2020-25684: 1 source package rows (dnsmasq); 25 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 15. https://security.alpinelinux.org/vuln/CVE-2020-25684
debian not yet assigned CVE-2020-25684 not yet assigned priority: Debian including 1 source packages (dnsmasq), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-25684
gentoo normal CVE-2020-25684: 1 GLSA(s) (202101-17), 1 atom(s) (net-dns/dnsmasq); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-25684
redhat medium — https://access.redhat.com/security/cve/CVE-2020-25684
suse high CVE-2020-25684 severity important: SUSE including 27 source package names (0.38.1.5.8.40:dnsmasq-2.78-7.6.1, 0.45.0.8.14.1:dnsmasq-2.78-7.6.1, …), 66 product×package rows across 54 product lines (Container suse/sles/15.2/virt-launcher, Container suse/sles/15.3/virt-launcher, … (54 product lines)): Fixed 66. https://www.suse.com/security/cve/CVE-2020-25684/
ubuntu medium CVE-2020-25684 medium priority: Ubuntu including 1 source packages (dnsmasq), 15 status rows across 15 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): released 14, ignored 1. https://ubuntu.com/security/CVE-2020-25684

Affected software / configurations for CVE-2020-25684

Vendor Product Version Raw CPE
thekelleys dnsmasq < 2.83 cpe:2.3:a:thekelleys:dnsmasq:*:*:*:*:*:*:*:*
fedoraproject fedora 32 cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
arista eos >= 4.21, < 4.21.14m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.22, < 4.22.9m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.23, < 4.23.7m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.24, < 4.24.5m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.25, < 4.25.2f cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*

References for CVE-2020-25684

URL Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1889686 Issue Tracking Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00027.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
https://security.gentoo.org/glsa/202101-17 Third Party Advisory
https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61 Third Party Advisory
https://www.debian.org/security/2021/dsa-4844 Third Party Advisory
https://www.jsof-tech.com/disclosures/dnspooq/ Third Party Advisory
https://www.kb.cert.org/vuls/id/434904
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