CVE-2026-100784
HIGHCVSS 8.8/10EPSS 0.34%
Last modified
CVE-2026-100784 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.. EPSS estimates a 0.34% chance of exploitation in the next 30 days.
Description
Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
Metrics
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 115.42.0 |
| Mozilla | Firefox | >= 116.0, < 140.17.0 |
| Mozilla | Firefox | >= 141.0, < 153.4.0 |
| Mozilla | Firefox | >= 154.0.0, < 157.0.0 |
| Mozilla | Thunderbird | < 140.17.0 |
| Mozilla | Thunderbird | >= 141.0, < 153.4.0 |
| Mozilla | Thunderbird | >= 154.0, < 157.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2070264Permissions 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/mfsa2026-98/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-99/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-100784?
Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
How severe is CVE-2026-100784?
CVE-2026-100784 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.34% probability of exploitation in the next 30 days.
How do I fix CVE-2026-100784?
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.
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