Description
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Published: 2026-02-24
Score: 8.8 High
EPSS: < 1% Very Low
KEV: No
Impact: Potential Arbitrary Code Execution
Action: Immediate Patch
AI Analysis

Impact

A use‑after‑free defect exists in Mozilla’s JavaScript engine when executing WebAssembly modules. This weakness allows memory to be corrupted after an object has been freed, possibly enabling an attacker to influence program execution or corrupt data. The official description does not state the precise impact, so it is inferred that such corruption could lead to data integrity issues or compromise control flow, thereby creating a risk of arbitrary code execution.

Affected Systems

All standard releases of Mozilla Firefox and Thunderbird, as well as ESR branches before Firefox 148, ESR 140.8, Thunderbird 148, and ESR 140.8, are affected. Any version that does not include the patch for this use‑after‑free is vulnerable.

Risk and Exploitability

The CVSS score of 8.8 classifies the flaw as high severity. Its EPSS score is reported as less than 1 %, indicating a very low current probability of exploitation, and it is not included in the CISA KEV catalog. Based on the description, it is inferred that an attacker could trigger the defect by delivering a malicious WebAssembly module through a web page or an email attachment, giving remote code execution potential in a scriptable context. Consequently, organizations should treat this vulnerability as high‑risk and apply the vendor patch promptly.

Generated by OpenCVE AI on April 15, 2026 at 18:06 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply the latest Mozilla Firefox update (v148 or later, or ESR 140.8 or later).
  • Apply the latest Mozilla Thunderbird update (v148 or later, or ESR 140.8 or later).
  • If an update cannot be applied immediately, disable WebAssembly by setting javascript.options.wasm to false in about:config until a patch is available.

Generated by OpenCVE AI on April 15, 2026 at 18:06 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: WebAssembly component. This vulnerability affects Firefox < 148, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8. Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Sat, 28 Feb 2026 04:15:00 +0000

Type Values Removed Values Added
Metrics 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'}

 ssvc

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

cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'}

Wed, 25 Feb 2026 16:45:00 +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: WebAssembly component. This vulnerability affects Firefox < 148 and Firefox ESR < 140.8. Use-after-free in the JavaScript: WebAssembly component. This vulnerability affects Firefox < 148, 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: WebAssembly component. This vulnerability affects Firefox < 148 and Firefox ESR < 140.8.
Title Use-after-free in the JavaScript: WebAssembly component
References

Subscriptions

Mozilla Firefox Firefox Esr Thunderbird
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-04-13T13:53:16.679Z

Reserved: 2026-02-19T15:05:39.633Z

Link: CVE-2026-2767

cve-icon Vulnrichment

Updated: 2026-02-26T20:10:51.316Z

cve-icon NVD

Status : Modified

Published: 2026-02-24T14:16:25.080

Modified: 2026-04-13T15:17:22.853

Link: CVE-2026-2767

cve-icon Redhat

Severity : Important

Publid Date: 2026-02-24T13:33:05Z

Links: CVE-2026-2767 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-15T18:15:10Z

Weaknesses