SSLVersionMax

Set and lock the maximum version of TLS (Firefox defaults to a maximum of TLS 1.3).

Compatibility: Firefox 66, Firefox ESR 60.6
CCK2 Equivalent: N/A
Preferences Affected: security.tls.version.max

Windows (GPO)

Software\Policies\Mozilla\Firefox\SSLVersionMax = "tls1" | "tls1.1" | "tls1.2" | "tls1.3"

Windows (Intune)

OMA-URI:

./Device/Vendor/MSFT/Policy/Config/Firefox~Policy~firefox/SSLVersionMax

Value (string):

<enabled/>
<data id="SSLVersion" value="tls1 | tls1.2 | tls1.3"/>

macOS

<dict>
  <key>SSLVersionMax</key>
  <string>tls1 | tls1.1 | tls1.2 | tls1.3</string>
</dict>

policies.json

{
  "policies": {
    "SSLVersionMax": "tls1" | "tls1.1" | "tls1.2" | "tls1.3"
  }
}