CVE-2026-2758: Use-after-free in the JavaScript: GC component

Published Feb 24, 2026
·
Updated

Use-after-free in the JavaScript: GC component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8.

Other sources

Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

— MITRE

Affected Software

10 affected componentsFixes available
Mozilla Firefox<148
148
Mozilla Firefox ESR<140.8
140.8
Mozilla Firefox ESR<115.33
115.33
Mozilla Thunderbird<148
148
Mozilla Thunderbird<140.8
140.8
Mozilla Firefox<115.33.0
Mozilla Firefox<148.0
Mozilla Firefox>=128.0<140.8.0
Mozilla Thunderbird<140.8.0
Mozilla Thunderbird<148.0

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 148
  2. Upgrade

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

    Fixed in 140.8
  3. Upgrade

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

    Fixed in 115.33
  4. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 148
  5. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 115.33
  6. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.8
  7. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 148
  8. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 140.8

Event History

Feb 24, 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·01:32 PM
Data Sourced
via MITRE·01:32 PM
Description
Data Sourced
via Red Hat·02:05 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 PM
DescriptionSeverityWeaknessAffected Software
Jan 4, 58137
Event
via FIRST·07:56 PM

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

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Frequently Asked Questions

1

What is the severity of CVE-2026-2758?

CVE-2026-2758 is considered a high-severity vulnerability due to its potential for exploitation through a use-after-free condition.

2

How do I fix CVE-2026-2758?

To fix CVE-2026-2758, update your Firefox to version 148 or Firefox ESR to 140.8 or higher.

3

What versions of Firefox are affected by CVE-2026-2758?

CVE-2026-2758 affects Firefox versions prior to 148, as well as Firefox ESR versions prior to 115.33 and 140.8.

4

What components are impacted by CVE-2026-2758?

CVE-2026-2758 impacts the JavaScript garbage collection (GC) component of affected Firefox versions.

5

Is CVE-2026-2758 the only vulnerability affecting Firefox?

No, CVE-2026-2758 is one of several vulnerabilities that can affect different versions of Firefox.

Company

Resources

Contact

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