CVE-2026-100821
MEDIUMCVSS 4.7/10EPSS 0.15%
Last modified
CVE-2026-100821 is a medium-severity vulnerability rated 4.7/10 on the CVSS scale. Site isolation issue in the Panning and Zooming 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 0.15% chance of exploitation in the next 30 days.
Description
Site isolation issue in the Panning and Zooming 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 | >= 116.0.0, < 140.17.0 |
| Mozilla | Firefox | >= 141.0.0, < 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=2071784Permissions 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-2026-100821?
Site isolation issue in the Panning and Zooming 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-2026-100821?
CVE-2026-100821 has a CVSS score of 4.7/10 (MEDIUM severity). The EPSS model estimates a 0.15% probability of exploitation in the next 30 days.
How do I fix CVE-2026-100821?
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
- Same Subject, Wrong User: A Cross-Issuer Account Takeover in n8nStrix found an identity-binding bug in n8n's token-exchange flow enabling account takeover.
- 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-2026-100816Site isolation issue in the DOM: Networking component. This …8.1
- CVE-2026-100817Other issue in the JavaScript: WebAssembly component. This v…5.4
- CVE-2026-100818Sandbox escape due to use-after-free in the Widget: Gtk comp…9.6
- CVE-2026-100819Sandbox escape due to incorrect boundary conditions in the X…9.6
- CVE-2026-10082The Advanced Ads WordPress plugin before 2.0.23 does not sa…6.1
- CVE-2026-100820Privilege escalation in the Address Bar component. This vuln…8.8
- CVE-2026-100822Spoofing issue in the Networking: HTTP component. This vulne…5.4
- CVE-2026-100823Spoofing issue in the Downloads component in Firefox for And…5.4
- CVE-2026-100824Privilege escalation in the Places component. This vulnerabi…8.8
- CVE-2026-100825Use-after-free in the JavaScript Engine: JIT component. This…8.8
- CVE-2026-100826Denial-of-service in the Storage: StorageManager component. …6.5
- CVE-2026-100828Mitigation bypass in the Bookmarks & History component. This…9.6
Are you affected by CVE-2026-100821?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST