Threat Investigation
Request a demo

CVE-2026-16405

High

Description

Information disclosure in the Networking: WebSockets component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

SeverityHigh
CVSS7.5
Exploit probability—
ProductMozilla Firefox
PublishedJul 21, 2026
First seenJul 21, 2026
Weakness typeCWE-200Sensitive information exposure

How to fix

Update
  • mozilla firefox153.0.0, 140.13.0 or later

Affected products

ProductAffected versionsFixed in
mozilla firefoxv < 153.0.0, 140.1.0 ≤ v < 140.13.0153.0.0, 140.13.0

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.