STIGQter: STIG Summary: Mozilla Firefox Security Technical Implementation Guide Version: 6 Release: 8 Benchmark Date: 01 Jul 2026:

Firefox encrypted media extensions must be disabled.

DISA Rule

SV-251581r960963_rule

Vulnerability Number

V-251581

Group Title

SRG-APP-000141

Rule Version

FFOX-00-000037

Severity

CAT II

CCI(s)

• CCI-000381 - Configure the system to provide only organization-defined mission essential capabilities.

Weight

10

Fix Recommendation

Windows group policy:
1. Open the group policy editor tool with "gpedit.msc".
2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox\Encrypted Media Extensions
Policy Name: Enable Encrypted Media Extensions
Policy State: Disabled
Policy Name: Lock Encrypted Media Extensions
Policy State: Enabled

macOS "plist" file:
<key>EncryptedMediaExtensions</key>
<dict>
<key>Enabled</key>
<false/>
<key>Locked</key>
<true/>

Linux "policies.json" file:
Add the following in the policies section:
"EncryptedMediaExtensions": {
"Enabled": false,
"Locked": true
}

Check Contents

Type "about:policies" in the browser address bar.

If "EncryptedMediaExtensions" is not displayed under Policy Name or the Policy Value does not have "Enabled" set to "false" or the Policy Value does not have "Locked" set to "true", this is a finding.

Vulnerability Number

V-251581

Documentable

False

Rule Version

FFOX-00-000037

Severity Override Guidance

Type "about:policies" in the browser address bar.

If "EncryptedMediaExtensions" is not displayed under Policy Name or the Policy Value does not have "Enabled" set to "false" or the Policy Value does not have "Locked" set to "true", this is a finding.

Check Content Reference

M

Target Key

5446