CVE-2020-26961
This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
Does this matter?
Lower severity and a low EPSS score (1.17%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
- EPSS
- 1.17% probability · 67th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Affected
- mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird
- Source
- security@mozilla.org
EPSS 1.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1672528Issue Tracking, Permissions Required, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-50/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-51/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-52/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1672528Issue Tracking, Permissions Required, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-50/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-51/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-52/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.