CVE-2026-100776
HIGHCVSS 8.8/10EPSS 0.33%
Last modified
CVE-2026-100776 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.. EPSS estimates a 0.33% chance of exploitation in the next 30 days.
Description
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
Metrics
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | >= 140.0.0, < 140.17.0 |
| Mozilla | Firefox | >= 153.0.0, < 153.4.0 |
| Mozilla | Firefox | >= 154.0.0, < 157.0.0 |
| Mozilla | Thunderbird | >= 140.0, < 140.17.0 |
| Mozilla | Thunderbird | >= 153.0, < 153.4.0 |
| Mozilla | Thunderbird | >= 154.0, < 157.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2068374Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-100/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-101/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-102/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-103/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-97/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-99/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-100776?
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
How severe is CVE-2026-100776?
CVE-2026-100776 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.33% probability of exploitation in the next 30 days.
How do I fix CVE-2026-100776?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-100770Sandbox escape due to use-after-free in the DOM: Content Pro…9.6
- CVE-2026-100771Undefined behavior in the DOM: Streams component. This vulne…8.1
- CVE-2026-100772Use-after-free in the DOM: Core & HTML component. This vulne…8.8
- CVE-2026-100773Use-after-free in the Storage: IndexedDB component. This vul…8.8
- CVE-2026-100774Use-after-free in the DOM: Core & HTML component. This vulne…8.8
- CVE-2026-100775Sandbox escape in the Graphics component. This vulnerability…9.6
- CVE-2026-100777Use-after-free in the Graphics: Canvas2D component. This vul…8.8
- CVE-2026-100778Sandbox escape due to use-after-free in the DOM: Core & HTML…9.6
- CVE-2026-100779Use-after-free in the XSLT component. This vulnerability was…8.8
- CVE-2026-10078A flaw was found in the Quay config-tool's GitLab OAuth vali…2.7
- CVE-2026-100780Use-after-free in the DOM: Core & HTML component. This vulne…8.8
- CVE-2026-100781Sandbox escape due to incorrect boundary conditions in the G…9.6
Are you affected by CVE-2026-100776?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST