CVE-2026-117991
Low risk· EPSS 8%Exploitation Probability (EPSS)
Low risk8th percentile - higher than 8% of all known CVEs
Summary
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.
Risk Assessment
Incorrect boundary conditions can lead to memory corruption and potential code execution or application crashes when processing text and fonts. Organizations running vulnerable versions are exposed to attacks via malicious web pages or messages.
Recommendation
Update Firefox to version 159 or ESR 153.6 and Thunderbird to version 159 or 153.6. Prioritize workstations with internet and email access.
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-2026-117990Low 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.
- CVE-2026-117989Low risk· EPSS 8%
A use-after-free vulnerability exists in the Graphics component of Firefox and Thunderbird. It was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
Original NVD description (English source)
Incorrect boundary conditions in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS