CVE-2026-12304

Same-origin policy bypass in the Networking: Cookies component

Critical · published June 16, 2026

CVSS v3.1
9.1
EPSS
0%
Percentile
8.1
In the wild
Unconfirmed
What it is

Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

The record
Technical detail
CVSS v3.1
9.1 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00189 · 8.1th percentile
Published
2026-06-16T11:52Z
EPSS history
Timeline
  • 16 JUN 11:52Z
    Same-origin policy bypass in the Networking: Cookies component
    cvelistv5