High CVSS 8.8
CVE-2026-16396
Privilege escalation in WebExtensions. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.
What this means
- Exposure
- Exploitable remotely over the network and without authentication — but only if a user opens booby-trapped content.
- Impact
- An attacker can read sensitive data, modify or destroy data and take the service offline.
- Weakness
- Privilege handling is faulty, so an account ends up with more rights than intended.
- Likelihood
- Its EPSS score stays low: nothing points to imminent exploitation, which is no reason to leave it unpatched.
What to doFold into the next patch cycle.
Read automatically from the CVSS vector, the weakness type (CWE) and the EPSS score. The technical description above remains the one published by NIST.