CVE-2026-100821
Received Received - Intake

Firefox Site Isolation Flaw in Panning and Zooming Component

Publication date: 2026-09-29

Last updated on: 2026-09-29

Assigner: Mozilla Corporation

Description
Site isolation issue in the Panning and Zooming component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

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Meta Information

Published
2026-09-29
Last Modified
2026-09-29
Generated
2026-09-29
AI Q&A
2026-09-29
EPSS Evaluated
N/A
NVD
CVE-2026-100821
EUVD
EUVD-2026-88800

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
mozilla firefox 153.4
mozilla firefox 157
mozilla firefox 115.42
mozilla firefox 140.17

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a site isolation issue in the Panning and Zooming component of Firefox. Site isolation is a security feature that separates content from different websites to prevent malicious sites from accessing data from other sites. A flaw in this component could allow unauthorized access between sites.

Detection Guidance

Detection requires checking Firefox version against patched releases. Compare installed version with Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, or Firefox ESR 140.17. Use commands like 'firefox --version' or check 'about:support' in Firefox.

Impact Analysis

An attacker could exploit this to access sensitive data from other websites you have open, such as cookies, session tokens, or personal information. This could lead to account hijacking, data theft, or unauthorized actions on your behalf.

Mitigation Strategies

Update Firefox to the latest patched version immediately. For ESR users, upgrade to Firefox ESR 153.4 or 115.42. For standard releases, upgrade to Firefox 157 or ESR 140.17. Disable unnecessary extensions if updates are delayed.

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