Critical severity · published Sep 15, 2026
CVE-2026-92038
Mitigation bypass in the Remote Settings Client component
9.1
CVSS
0.3%
EPSS
No
On KEV
Description
Mitigation bypass in the Remote Settings Client component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
Firefox · Mozilla
before 153.3.0; 154.0.0 before 156.0.0 · source: NVD
TH
Thunderbird · Mozilla
before 153.3.0; 154.0 before 156.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-92038
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-92038
Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=2068952
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-90/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-93/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-94/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-96/
More from Firefox
10.0
CVE-2019-11708
Mozilla Firefox and Thunderbird Sandbox Escape Vulnerability
9.8
CVE-2024-9680
Mozilla Firefox Use-After-Free Vulnerability
9.8
CVE-2010-3765
Mozilla Multiple Products Remote Code Execution Vulnerability
9.6
CVE-2022-26486
Mozilla Firefox Use-After-Free Vulnerability
8.8
CVE-2023-5217
Google Chromium libvpx Heap Buffer Overflow Vulnerability