Log in Start free

Vulnerability · Published Dec 9, 2020 · Assigned by mozilla

CVE-2020-26961

Medium 6.5

In plain English

A medium-severity security flaw in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 67% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)6.5Medium
Exploit odds (30 days)1.2%top 32.6% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

When DNS over HTTPS is in use, it intentionally filters RFC1918 and related IP ranges from the responses as these do not make sense coming from a DoH resolver. However when an IPv4 address was mapped through IPv6, these addresses were erroneously let through, leading to a potential DNS Rebinding attack. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.20firefox83.0-r0ALPINE-CVE-2020-26961
Alpine:v3.21firefox83.0-r0ALPINE-CVE-2020-26961
Alpine:v3.22firefox83.0-r0ALPINE-CVE-2020-26961
Alpine:v3.23firefox83.0-r0ALPINE-CVE-2020-26961
Alpine:v3.20firefox-esr78.5.0-r0ALPINE-CVE-2020-26961
Alpine:v3.21firefox-esr78.5.0-r0ALPINE-CVE-2020-26961
Alpine:v3.22firefox-esr78.5.0-r0ALPINE-CVE-2020-26961
Alpine:v3.23firefox-esr78.5.0-r0ALPINE-CVE-2020-26961
Alpine:v3.21librewolf83.0-r0ALPINE-CVE-2020-26961
Alpine:v3.22librewolf83.0-r0ALPINE-CVE-2020-26961
Alpine:v3.23librewolf83.0-r0ALPINE-CVE-2020-26961
Alpine:v3.24librewolf83.0-r0ALPINE-CVE-2020-26961
Alpine:v3.20thunderbird78.5.1-r0ALPINE-CVE-2020-26961
Alpine:v3.21thunderbird78.5.1-r0ALPINE-CVE-2020-26961
Alpine:v3.22thunderbird78.5.1-r0ALPINE-CVE-2020-26961
Alpine:v3.23thunderbird78.5.1-r0ALPINE-CVE-2020-26961
Debian:12firefox-esr78.5.0esr-1DEBIAN-CVE-2020-26961
Debian:13firefox-esr78.5.0esr-1DEBIAN-CVE-2020-26961
Debian:14firefox-esr78.5.0esr-1DEBIAN-CVE-2020-26961
Debian:12thunderbird1:78.5.0-1DEBIAN-CVE-2020-26961
Debian:13thunderbird1:78.5.0-1DEBIAN-CVE-2020-26961
Debian:14thunderbird1:78.5.0-1DEBIAN-CVE-2020-26961

Affected products (as reported)

VendorProductVersions
Mozilla Firefox < 83
Mozilla Firefox ESR < 78.5
Mozilla Thunderbird < 78.5

References