CVE-2026-8950

Same-origin policy bypass in the Networking: HTTP component

State: Published
Severity: 9.3 Critical
Published: May 19, 2026
Updated: May 19, 2026
Reserved: May 19, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	9.3 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N	CISA-ADP

Weaknesses

CWE-346 Origin Validation Error

Affected Products

Product	Versions
FirefoxMozilla	140.11 through 140.*Not affected 151 and laterNot affected
ThunderbirdMozilla	140.11 through 140.*Not affected 151 and laterNot affected

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/

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.