CVE-2026-109763: Mitigation bypass in the File Handling component

Published Oct 13, 2026
·
Updated

Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.

Affected Software

2 affected componentsFixes available
Mozilla Firefox<158
158
Mozilla Firefox ESR<153.5
153.5

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 158
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 153.5
  3. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 158
  4. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 153.5

Event History

Oct 13, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
CVE Published
via MITRE·12:29 PM
Data Sourced
via MITRE·12:29 PM
Description
Data Sourced
via NVD·01:17 PM
Description

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

Which Firefox releases contain the fix?

The vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.

2

Which products should be checked during triage?

Check deployments of Mozilla Firefox and Mozilla Firefox ESR. Versions earlier than the listed fixed releases should be evaluated for exposure.

Company

Resources

Contact

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