CVE-2025-4092
MediumCVSS 6.5Exploitation Probability (EPSS)
Low risk21th percentile - higher than 21% of all known CVEs
Summary
Memory safety bugs present in Firefox 137 and Thunderbird 137. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 138 and Thunderbird 138.
Risk Assessment
An attacker could exploit memory corruption to execute arbitrary code in the context of the browser or mail client, leading to full compromise of the user's system. This affects confidentiality, integrity, and availability.
Recommendation
Update Firefox and Thunderbird to version 138 or later. After updating, restart the applications to apply the fixes.
Other vulnerabilities in Firefox, Thunderbird
See all- CVE-2026-16408Critical
Integer overflow in the Audio/Video: Playback component in Firefox and Thunderbird. Fixed in versions 153.
- CVE-2026-16395Critical
Integer overflow in the Audio/Video component in Firefox and Thunderbird. Fixed in versions 153.
- CVE-2026-6770Medium
A security issue exists in the Storage: IndexedDB component of the Firefox browser and the Thunderbird mail client. The vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
- CVE-2026-4729Critical
Memory safety bugs were found in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption, which could potentially allow arbitrary code execution. The vulnerabilities were fixed in Firefox 149 and Thunderbird 149.
- CVE-2026-4720Critical
Memory safety bugs were found in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and could potentially be exploited to run arbitrary code with enough effort.
- CVE-2026-2807Critical
Memory safety bugs were found in Firefox 147 and Thunderbird 147. Some of these bugs showed evidence of memory corruption and could potentially be exploited to run arbitrary code. The vulnerability was fixed in Firefox 148 and Thunderbird 148.
- CVE-2026-2792Critical
Memory safety bugs were found in Firefox ESR 140.7, Firefox 147, Thunderbird ESR 140.7, and Thunderbird 147. Some of these bugs showed evidence of memory corruption and could potentially be exploited to run arbitrary code with enough effort.
- CVE-2026-118008High
Privilege escalation vulnerability in the DOM: Navigation component. It was fixed in Firefox 159 and Thunderbird 159.
- CVE-2026-117991Low risk· EPSS 8%
The vulnerability stems from incorrect boundary conditions in the Layout: Text and Fonts component of Firefox and Thunderbird. It was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
- CVE-2026-117990Low risk· EPSS 8%
The vulnerability allows a sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component. It was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
Original NVD description (English source)
Memory safety bugs present in Firefox 137 and Thunderbird 137. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 138 and Thunderbird 138.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS