CVE-2026-8950

CRITICAL

Same-origin policy bypass in the Networking: HTTP component

Title source: cna

Description

Same-origin policy bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

References (5)

Core 5

Core References

https://bugzilla.mozilla.org/show_bug.cgi?id=1965430

https://www.mozilla.org/security/advisories/mfsa2026-46/

https://www.mozilla.org/security/advisories/mfsa2026-48/

https://www.mozilla.org/security/advisories/mfsa2026-50/

https://www.mozilla.org/security/advisories/mfsa2026-51/

Scores

CVSS v3 9.3

EPSS 0.0002

EPSS Percentile 4.4%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-346

Status published

Products (8)

mozilla/firefox < 140.11.0

mozilla/firefox < 151.0.0

Mozilla/Firefox 140.11 - 140.*

Mozilla/Firefox 151

mozilla/thunderbird < 140.11

mozilla/thunderbird < 151.0.0

Mozilla/Thunderbird 140.11 - 140.*

Mozilla/Thunderbird 151

Published May 19, 2026

Tracked Since May 19, 2026