CVE-2020-26961

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.

6.5

CVSS

Severity: Medium

CVSS 3.1 •

CVSS 2.0 •

EPSS 0.27%

Vendor Advisory mozilla.org Vendor Advisory mozilla.org Vendor Advisory mozilla.org Vendor Advisory mozilla.org

Affected: Mozilla Firefox

Affected: Mozilla Firefox ESR

Affected: Mozilla Thunderbird

References

Link	Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1672528	vendor advisory issue tracking permissions required
https://www.mozilla.org/security/advisories/mfsa2020-50/	vendor advisory
https://www.mozilla.org/security/advisories/mfsa2020-52/	vendor advisory
https://www.mozilla.org/security/advisories/mfsa2020-51/	vendor advisory

Frequently Asked Questions

What is the severity of CVE-2020-26961?: CVE-2020-26961 has been scored as a medium severity vulnerability.
How to fix CVE-2020-26961?: To fix CVE-2020-26961, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2020-26961 being actively exploited in the wild?: As for now, there are no information to confirm that CVE-2020-26961 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2020-26961?: CVE-2020-26961 affects Mozilla Firefox, Mozilla Firefox ESR, Mozilla Thunderbird.

This platform uses data from the NIST NVD, MITRE CVE, MITRE CWE, First.org and CISA KEV but is not endorsed or certified by these entities. CVE is a registred trademark of the MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. CWE is a registred trademark of the MITRE Corporation and the authoritative source of CWE content is MITRE's CWE web site.