ReviewHigh

CVE-2026-74978

Mozilla Firefox, Thunderbird, firefox

Clickjacking issue in the Widget component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

PRIORITY ASSESSMENT

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability-

Technical severityCVSS 8.1

Clickjacking issue in the Widget component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

Product: Mozilla Firefox, Thunderbird, firefox
Affected versions: < 153.1.0
Fixed versions: Verify the fixed release separately for each affected product line

Confirm exposure before applying a vendor-supported change.

1
Identify
Confirm that Mozilla Firefox, Thunderbird, firefox and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.