Is Use After Free affected by CVE-2026-2786?

A critical use-after-free vulnerability in Firefox and Thunderbird JavaScript engines (CVE-2026-2786, CVSS 9.8) poses severe risk to any organization using these applications, as it enables remote code execution with no user interaction required.

CVE-2026-2786

Q: How to fix CVE-2026-2786?

Within 24 hours: Inventory all Firefox and Thunderbird deployments; disable JavaScript execution where operationally feasible or restrict to trusted sites only; communicate risk to end-users. Within 7 days: Implement network-based restrictions on Firefox/Thunderbird auto-update mechanisms to prepare for rapid patching; consider isolating high-risk users' machines on segmented networks. Within 30 days: Deploy available vendor patches immediately upon release; conduct forensic analysis for signs of exploitation; review browser usage policies and consider mandatory upgrades to patched versions.

CRITICAL

2026-02-24 [email protected]

9.8

CVSS 3.1

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Patch Released

Apr 10, 2026 - 08:30 nvd

Patch available

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

CVE Published

Feb 24, 2026 - 14:16 nvd

CRITICAL 9.8

Description

Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 148, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.

Analysis

Use-after-free in Firefox JavaScript Engine before 148. Fourth distinct JS engine UAF in this release.

Remediation

Within 24 hours: Inventory all Firefox and Thunderbird deployments; disable JavaScript execution where operationally feasible or restrict to trusted sites only; communicate risk to end-users. Within 7 days: Implement network-based restrictions on Firefox/Thunderbird auto-update mechanisms to prepare for rapid patching; consider isolating high-risk users' machines on segmented networks. …

Analysis

Detailed AI-generated intelligence summary covering attack vector, impact assessment, affected versions, remediation steps, and indicators of compromise.

POChttps://••••••••••.com/exploit

PATCHhttps://••••••••••.com/patch

ADVISORYhttps://••••••••••.com/advisory

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Priority Score

Low Medium High Critical

KEV: 0

EPSS: +0.0

CVSS: +49

POC: 0

Vendor Status

CVE-2026-2786 vulnerability details – vuln.today

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CVE-2026-2786

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CVE-2026-2786

CVSS Vector

Lifecycle Timeline

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Description

Analysis

Remediation

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External POC / Exploit Code