SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2026-16365

Privilege escalation in the DOM: Workers component.

HIGH 8.8EPSS 0.28%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.28%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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.

CVSS 3.1
8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS
0.28% probability · 20th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-269, CWE-284
Affected
mozilla/firefox · mozilla/thunderbird
Source
security@mozilla.org
EPSS trend
0%3%5%27 October 2026: 0.28%27 October 202627 October 2026

EPSS 0.3% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.