#VU48466 Improperly implemented security check for standard in Mozilla Firefox and Firefox ESR


Published: 2020-11-17

Vulnerability identifier: #VU48466

Vulnerability risk: Medium

CVSSv3.1:

CVE-ID: CVE-2020-26961

CWE-ID: CWE-358

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Firefox
Client/Desktop applications / Web browsers
Firefox ESR
Client/Desktop applications / Web browsers

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to perform a DNS rebinding attack.

The vulnerability exists due to the way Firefox filters IPv4 mapped IP addresses. 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.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 60.0 - 82.0.3

Firefox ESR: 78.0 - 78.4.1, 68.0 - 68.12.0, 60.0 - 60.9.0


CPE

External links
http://www.mozilla.org/en-US/security/advisories/mfsa2020-50/
http://www.mozilla.org/en-US/security/advisories/mfsa2020-51/


Q & A

Can this vulnerability be exploited remotely?

Is there known malware, which exploits this vulnerability?


Latest bulletins with this vulnerability