Description
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.
Published: 2026-02-24
Score: 9.8 Critical
EPSS: < 1% Very Low
KEV: No
Impact: Arbitrary code execution
Action: Apply patch
AI Analysis

Impact

Use after free occurs in the JavaScript garbage collector component in Mozilla Firefox and Thunderbird. The CVE description does not explicitly state the consequences; however, use‑after‑free flaws can lead to execution of arbitrary code or crashes, potentially impacting confidentiality, integrity, or availability. This potential impact is inferred from typical behavior of this class of vulnerability.

Affected Systems

The flaw affects all releases of Mozilla Firefox and Mozilla Thunderbird that were published before the patches. The vulnerability is fixed in Firefox 148, Firefox ESR 115.33 and 140.8, and in Thunderbird 148 and Thunderbird ESR 140.8.

Risk and Exploitability

The CVSS score is 9.8, indicating high severity, while the EPSS score is less than 1 %, suggesting a low likelihood of current exploitation. The CVE description does not specify an attack vector; it is inferred that malicious JavaScript delivered via a web page or crafted email could be a potential method. The vulnerability is not listed in the CISA KEV catalog.

Generated by OpenCVE AI on April 15, 2026 at 16:14 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Update Firefox to version 148 or later or to ESR 115.33/140.8, and update Thunderbird to version 148 or later or to ESR 140.8.
  • Restart affected applications to ensure the new versions are in use.
  • If an immediate update is not possible, limit execution of JavaScript on untrusted sites or filter email for malicious content as an inferred temporary mitigation.

Generated by OpenCVE AI on April 15, 2026 at 16:14 UTC.

Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4495-1 thunderbird security update
Debian DLA Debian DLA DLA-4496-1 firefox-esr security update
Debian DSA Debian DSA DSA-6148-1 firefox-esr security update
Debian DSA Debian DSA DSA-6152-1 thunderbird security update
History

Mon, 13 Apr 2026 14:30:00 +0000

Type Values Removed Values Added
Description Use-after-free in the JavaScript: GC component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8. 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.

Fri, 27 Feb 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Wed, 25 Feb 2026 17:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

 cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Wed, 25 Feb 2026 12:00:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Mozilla firefox Esr
Mozilla thunderbird
Vendors & Products Mozilla
Mozilla firefox
Mozilla firefox Esr
Mozilla thunderbird

Wed, 25 Feb 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

threat_severity

Important

Tue, 24 Feb 2026 18:00:00 +0000

Type Values Removed Values Added
Description Use-after-free in the JavaScript: GC component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. Use-after-free in the JavaScript: GC component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
References

Tue, 24 Feb 2026 14:00:00 +0000

Type Values Removed Values Added
Description Use-after-free in the JavaScript: GC component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8.
Title Use-after-free in the JavaScript: GC component
References

Subscriptions

Mozilla Firefox Firefox Esr Thunderbird
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-04-15T15:37:39.628Z

Reserved: 2026-02-19T15:05:18.397Z

Link: CVE-2026-2758

cve-icon Vulnrichment

Updated: 2026-02-26T15:44:52.221Z

cve-icon NVD

Status : Modified

Published: 2026-02-24T14:16:24.037

Modified: 2026-04-13T15:17:20.577

Link: CVE-2026-2758

cve-icon Redhat

Severity : Important

Publid Date: 2026-02-24T13:32:58Z

Links: CVE-2026-2758 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-15T17:15:10Z

Weaknesses