Same-Origin Policy Bypass in Firefox Networking Component
CVE-2026-2790

8.8HIGH

Key Information:

Vendor

Mozilla
Status
Firefox
Firefox Esr
Thunderbird
Vendor
CVE Published:
24 February 2026

What is CVE-2026-2790?

A vulnerability exists in the Networking component of Firefox, allowing attackers to bypass the same-origin policy. This issue affects users of Firefox versions prior to 148 and Firefox ESR versions before 140.8, enabling potential unauthorized access to sensitive data across domains, thereby posing a significant risk to user privacy and security.

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Affected Version(s)

Firefox < 148

Firefox ESR < 140.8

Thunderbird < 148

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2008426
https://www.mozilla.org/security/advisories/mfsa2026-13/
https://www.mozilla.org/security/advisories/mfsa2026-15/

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Surya Dev Singh
JSON
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