Spoofing Vulnerability in Firefox from Mozilla
CVE-2026-100822

5.4MEDIUM

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
29 September 2026

What is CVE-2026-100822?

A spoofing vulnerability exists in the Networking: HTTP component of Mozilla Firefox, which could allow an attacker to create misleading URLs or web content that could deceive users. This may lead to unauthorized actions or exposing sensitive information. Mozilla has addressed this issue in the Firefox ESR 153.4 and Firefox 157 releases, enhancing the security measures to prevent potential exploitation.

Affected Version(s)

Firefox 153.4

Firefox 157

Thunderbird 153.4

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2051115
https://www.mozilla.org/security/advisories/mfsa2026-100/
https://www.mozilla.org/security/advisories/mfsa2026-101/

CVSS V3.1

Score:
5.4
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Tomoya Nakanishi
.