CVE-2026-16365: Privilege escalation in the DOM: Workers component

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-21 · updated 2026-10-24
Weakness: CWE-269

Description

Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153, Thunderbird 153, Firefox ESR 140.15, and Thunderbird 140.15.

Affected products

Mozilla Firefox: before 153.0.0 — fixed in 153.0.0
Mozilla Thunderbird: before 153.0 — fixed in 153.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 153.0.0; Mozilla Thunderbird 153.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2049149
https://www.mozilla.org/security/advisories/mfsa2026-68/
https://www.mozilla.org/security/advisories/mfsa2026-71/
https://www.mozilla.org/security/advisories/mfsa2026-84/
https://www.mozilla.org/security/advisories/mfsa2026-87/

Get alerted when CVE-2026-16365 or the next vulnerability affects your stack