CVE catalog

CVE-2020-25685

dnsmasq: CVE-2020-25685

Severity: Medium · CVSS 5.4CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
Published: Jan 1, 2020, 12:00:00 AM UTC
Source: [NVD] · [CVE record]
EPSS: 2.23% · Oct 25, 2026

A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in forward.c:reply_query(), which is the forwarded query that matches the reply, by only using a weak hash of the query name. Due to the weak hash (CRC32 when dnsmasq is compiled without DNSSEC, SHA-1 when it is) this flaw allows an off-path attacker to find several different domains all having the same hash, substantially reducing the number of attempts they would have to perform to forge a reply and get it accepted by dnsmasq. This is in contrast with RFC5452, which specifies that the query name is one of the attributes of a query that must be used to match a reply. This flaw could be abused to perform a DNS Cache Poisoning attack. 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.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	dnsmasq	sid	`2.93-3`	fixed
Debian	dnsmasq	forky	`2.93-3`	fixed
Debian	dnsmasq	trixie	`2.91-1+deb13u2`	fixed
Debian	dnsmasq	trixie-security	`2.91-1+deb13u1`	fixed
Debian	dnsmasq	bookworm	`2.90-4~deb12u2`	fixed
Debian	dnsmasq	bookworm-security	`2.90-4~deb12u2`	fixed
Alpine	dnsmasq	3.10	`2.83-r0`	fixed
Alpine	dnsmasq	3.11	`2.83-r0`	fixed
Alpine	dnsmasq	3.12	`2.83-r0`	fixed
Alpine	dnsmasq	3.13	`2.83-r0`	fixed
Alpine	dnsmasq	3.14	`2.83-r0`	fixed
Alpine	dnsmasq	3.15	`2.83-r0`	fixed
Alpine	dnsmasq	3.16	`2.83-r0`	fixed
Alpine	dnsmasq	3.17	`2.83-r0`	fixed
Alpine	dnsmasq	3.18	`2.83-r0`	fixed
Alpine	dnsmasq	3.19	`2.83-r0`	fixed
Alpine	dnsmasq	3.20	`2.83-r0`	fixed
Alpine	dnsmasq	3.21	`2.83-r0`	fixed
Alpine	dnsmasq	3.22	`2.83-r0`	fixed
Alpine	dnsmasq	3.23	`2.83-r0`	fixed
Alpine	dnsmasq	3.24	`2.83-r0`	fixed
Ubuntu	dnsmasq	pro	`2.66-4ubuntu1`	vulnerable
Ubuntu	dnsmasq	pro	`2.67-1`	vulnerable
Ubuntu	dnsmasq	pro	`2.68-1`	vulnerable
Ubuntu	dnsmasq	pro	`2.68-1ubuntu0.1`	vulnerable
Ubuntu	dnsmasq	pro	`2.68-1ubuntu0.2`	vulnerable
Ubuntu	dnsmasq	pro	`2.68-1ubuntu0.2+esm1`	vulnerable
Ubuntu	dnsmasq	pro	`2.68-1ubuntu0.2+esm2`	vulnerable
Ubuntu	dnsmasq	pro	`2.68-1ubuntu0.2+esm3`	vulnerable
Ubuntu	dnsmasq	pro	`2.68-1ubuntu0.2+esm5`	vulnerable
Ubuntu	dnsmasq	pro	`2.68-1ubuntu0.2+esm6`	vulnerable
Ubuntu	dnsmasq	16.04	`2.75-1`	vulnerable
Ubuntu	dnsmasq	16.04	`2.75-1ubuntu0.16.04.1`	vulnerable
Ubuntu	dnsmasq	16.04	`2.75-1ubuntu0.16.04.2`	vulnerable
Ubuntu	dnsmasq	16.04	`2.75-1ubuntu0.16.04.3`	vulnerable
Ubuntu	dnsmasq	16.04	`2.75-1ubuntu0.16.04.4`	vulnerable
Ubuntu	dnsmasq	16.04	`2.75-1ubuntu0.16.04.5`	vulnerable
Ubuntu	dnsmasq	16.04	`2.75-1ubuntu0.16.04.7`	fixed
Ubuntu	dnsmasq	18.04	`2.78-1`	vulnerable
Ubuntu	dnsmasq	18.04	`2.78-3`	vulnerable
Ubuntu	dnsmasq	18.04	`2.79-1`	vulnerable
Ubuntu	dnsmasq	18.04	`2.79-1ubuntu0.2`	fixed
Ubuntu	dnsmasq	20.04	`2.80-1ubuntu2`	vulnerable
Ubuntu	dnsmasq	20.04	`2.80-1ubuntu4`	vulnerable
Ubuntu	dnsmasq	20.04	`2.80-1.1ubuntu1`	vulnerable
Ubuntu	dnsmasq	20.04	`2.80-1.1ubuntu1.2`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	dnsmasq	source	sid	`2.83-1`	not yet assigned	Not reported	Not reported
Debian	dnsmasq	source	forky	`2.83-1`	not yet assigned	Not reported	Not reported
Debian	dnsmasq	source	trixie	`2.83-1`	not yet assigned	Not reported	Not reported
Debian	dnsmasq	source	bookworm	`2.83-1`	not yet assigned	Not reported	Not reported
Alpine	dnsmasq	apk	3.10	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.11	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.12	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.13	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.14	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.15	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.16	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.17	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.18	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.19	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.20	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.21	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.22	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.23	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Alpine	dnsmasq	apk	3.24	`2.83-r0`	Not reported	ALPINE-CVE-2020-25685	Not reported
Ubuntu	dnsmasq	deb	16.04	`2.75-1ubuntu0.16.04.7`	Not reported	UBUNTU-CVE-2020-25685	Not reported
Ubuntu	dnsmasq	deb	18.04	`2.79-1ubuntu0.2`	Not reported	UBUNTU-CVE-2020-25685	Not reported
Ubuntu	dnsmasq	deb	20.04	`2.80-1.1ubuntu1.2`	Not reported	UBUNTU-CVE-2020-25685	Not reported

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

[Debian 12 (Bookworm)]

[dnsmasq]Unknown
Details (4)
- 2.90-4~deb12u2 · all · bookworm
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · all · bookworm
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · all · bookworm-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · all · bookworm-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
[dnsmasq-base]Unknown
Source package: [dnsmasq]
Details (4)
- 2.90-4~deb12u2 · amd64 · bookworm
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · arm64 · bookworm
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · amd64 · bookworm-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · arm64 · bookworm-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
[dnsmasq-base-lua]Unknown
Source package: [dnsmasq]
Details (4)
- 2.90-4~deb12u2 · amd64 · bookworm
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · arm64 · bookworm
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · amd64 · bookworm-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · arm64 · bookworm-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
[dnsmasq-utils]Unknown
Source package: [dnsmasq]
Details (4)
- 2.90-4~deb12u2 · amd64 · bookworm
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · arm64 · bookworm
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · amd64 · bookworm-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12
- 2.90-4~deb12u2 · arm64 · bookworm-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · bookworm; dsa · dnsmasq · debian · 12

[Debian 13 (Trixie)]

[dnsmasq]Unknown
Details (4)
- 2.91-1+deb13u1 · all · trixie
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · all · trixie
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · all · trixie-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · all · trixie-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
[dnsmasq-base]Unknown
Source package: [dnsmasq]
Details (4)
- 2.91-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
[dnsmasq-base-lua]Unknown
Source package: [dnsmasq]
Details (4)
- 2.91-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
[dnsmasq-utils]Unknown
Source package: [dnsmasq]
Details (4)
- 2.91-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13
- 2.91-1+deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 2.83-1
  dsa · dnsmasq · debian · 13

Observed: Oct 23, 2026, 5:49:50 PM UTC

References

[CERT-Bund public advisories] · [CISA cybersecurity advisories] · [Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]