CVE-2026-100757: Use-after-free in the Widget component

Published Sep 29, 2026
·
Updated

Use-after-free in the Widget component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

Affected Software

4 affected componentsFixes available
Mozilla Firefox ESR<115.42
115.42
Mozilla Firefox ESR<140.17
140.17
Mozilla Firefox<157
157
Mozilla Firefox ESR<153.4
153.4

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 115.42
  2. Upgrade

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

    Fixed in 140.17
  3. Upgrade

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

    Fixed in 157
  4. Upgrade

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

    Fixed in 153.4
  5. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 153.4
  6. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 157
  7. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 115.42
  8. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.17

Event History

Sep 29, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Updated
via Mozilla·12:00 AM
Affected Software
CVE Published
via MITRE·12:35 PM
Data Sourced
via MITRE·12:35 PM
Description
Data Sourced
via NVD·01:17 PM
DescriptionSeverityWeakness

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

Which deployments should be included in triage?

The affected software list identifies Mozilla Firefox and Mozilla Firefox ESR.

2

Where can remediation information be verified?

Review Mozilla Bugzilla issue 2049352 and the Mozilla security advisories MFSA 2026-98 and MFSA 2026-99.

Company

Resources

Contact

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