SB2020111730 - Improperly implemented security check for standard in firefox-esr (Alpine package)
Published: November 17, 2020
Security Bulletin ID
SB2020111730
Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Improperly implemented security check for standard (CVE-ID: CVE-2020-26961)
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.
Remediation
Install update from vendor's website.