dbcve.org
FirefoxWeb browser · Mozilla

CVE-2026-2785

CRITICAL · 9.8 CVSS v3.1 Published 2026-02-24
Fix available
A fix is available. Upgrade to 140.8.0 / 148.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Invalid pointer in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A critical invalid pointer vulnerability in the Mozilla JavaScript Engine allows remote attackers to execute arbitrary code via specially crafted JavaScript. The invalid pointer dereference enables memory corruption that can be exploited without authentication, achieving complete system compromise given the CVSS 9.8 severity.

MitigationOrganizations must immediately update affected systems: upgrade Firefox to version 148 or later, Firefox ESR to 140.8 or later, Thunderbird to version 148 or later, or Thunderbird ESR 140.8 or later. Deploy these updates enterprise-wide as a priority to eliminate the attack vector.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FirefoxWeb browser
Affected:< 140.8.0< 148.0
ThunderbirdApplication
Affected:< 140.8.0< 148.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Firefox version
    Open Firefox, click Help > About Firefox, or navigate to about:support in the address bar, or run 'firefox --version' from command line
    Affected if Version is below 140.8.0 or below 148.0 (any version lower than 140.8.0 or between 140.8.0 and 148.0)
  2. Identify installed Thunderbird version
    Open Thunderbird, click Help > About Thunderbird, or run 'thunderbird --version' from command line
    Affected if Version is below 140.8.0 or below 148.0 (any version lower than 140.8.0 or between 140.8.0 and 148.0)
  3. Check for multiple Firefox installations
    On Windows check Program Files and Program Files (x86) for multiple Firefox folders; on Linux check /usr/lib/firefox and /opt; on macOS check /Applications for multiple Firefox versions
    Affected if Any installed Firefox instance is found to be in the affected version range
  4. Enumerate Thunderbird across the environment
    Use system package manager (dpkg -l, rpm -qa, or chocolatey list) to list all installed Thunderbird packages and their versions
    Affected if Any Thunderbird installation matches the affected version ranges

The environment is affected if any installed instance of Mozilla Firefox or Thunderbird is version 140.8.0 or lower, or version 148.0 or lower but above 140.8.0.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 140.8.0 / 148.0 or later
Fixed in 140.8.0148.0
Interim mitigation

Organizations must immediately update affected systems: upgrade Firefox to version 148 or later, Firefox ESR to 140.8 or later, Thunderbird to version 148 or later, or Thunderbird ESR 140.8 or later. Deploy these updates enterprise-wide as a priority to eliminate the attack vector.

Recommended fix High confidence

Firefox 148 (standard) or Firefox ESR 140.8; Thunderbird 148 (standard) or Thunderbird 140.8 (ESR)

  1. Identify your current Firefox or Thunderbird version via Help > About (or run: firefox --version or thunderbird --version)
  2. For Firefox users: If you are on the standard release channel, upgrade to Firefox 148 or later
  3. For Firefox ESR users: Upgrade to Firefox ESR 140.8 or later
  4. For Thunderbird users: If you are on the standard release channel, upgrade to Thunderbird 148 or later
  5. For Thunderbird ESR users: Upgrade to Thunderbird 140.8 or later
  6. On Linux: Use your system package manager (e.g., sudo apt update && sudo apt upgrade firefox) or download from https://www.mozilla.org/firefox/download/
  7. On macOS: Use the built-in update mechanism via Firefox/Thunderbird > Check for Updates or download from https://www.mozilla.org/
  8. On Windows: Use the built-in update mechanism via Help > About Firefox/Thunderbird or download from https://www.mozilla.org/
Caveat Mozilla security updates typically contain no breaking changes; this is a routine security release

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-2785 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-2785 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data