Firefox must be configured to allow only TLS 1.2 or above.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
high	V-251546	SRG-APP-000560	FFOX-00-000002	SV-251546r961869_rule	2025-02-11	6

Description
Use of versions prior to TLS 1.2 are not permitted. SSL 2.0 and SSL 3.0 contain a number of security flaws. These versions must be disabled in compliance with the Network Infrastructure and Secure Remote Computing STIGs.

ℹ️ Check
Type "about:policies" in the browser window. If "SSLVersionMin" is not displayed under Policy Name or the Policy Value is not "tls1.2" or "tls1.3", this is a finding.

✔️ Fix
Windows group policy: 1. Open the group policy editor tool with "gpedit.msc". 2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox\ Policy Name: Minimum SSL version enabled Policy State: Enabled Policy Value: TLS 1.2 (or TLS 1.3) macOS "plist" file: Add the following: <key>SSLVersionMin</key> <string>tls1.2</string> (or <string>tls1.3</string>) Linux "policies.json" file: Add the following in the policies section: "SSLVersionMin": "tls1.2" or ("SSLVersionMin": "tls1.3")

✔️ Fix

Windows group policy: 1. Open the group policy editor tool with "gpedit.msc". 2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox\ Policy Name: Minimum SSL version enabled Policy State: Enabled Policy Value: TLS 1.2 (or TLS 1.3) macOS "plist" file: Add the following: <key>SSLVersionMin</key> <string>tls1.2</string> (or <string>tls1.3</string>) Linux "policies.json" file: Add the following in the policies section: "SSLVersionMin": "tls1.2" or ("SSLVersionMin": "tls1.3")