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FirefoxWeb browser · Mozilla

CVE-2026-2805

CRITICAL · 9.8 CVSS v3.1 Published 2026-02-24
Fix available
A fix is available. Upgrade to 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 DOM: Core & HTML component. This vulnerability was fixed in Firefox 148 and Thunderbird 148.

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

An invalid pointer vulnerability in the DOM (Document Object Model) processing within Firefox and Thunderbird's Core & HTML components allows memory corruption, likely leading to remote code execution. The critical CVSS 9.8 indicates this can be exploited remotely without user interaction beyond visiting malicious content.

MitigationUpgrade to Firefox 148 or Thunderbird 148 to remediate this vulnerability. Organizations should inventory all installations and deploy the updates immediately.

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:< 148.0
ThunderbirdApplication
Affected:< 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 Mozilla product
    Check if Firefox or Thunderbird is installed on the system. On Windows, look in Program Files for Mozilla Firefox or Mozilla Thunderbird. On Linux, run 'which firefox' or 'which thunderbird'. On macOS, check /Applications for Firefox.app or Thunderbird.app.
    Affected if Either Firefox or Thunderbird is present on the system
  2. Check Firefox version number
    For Firefox: Open about:support in the address bar, or run 'firefox --version' from command line, or check the executable properties. Record the full version number (e.g., 147.0.1).
    Affected if Firefox version is installed and is less than 148.0
  3. Check Thunderbird version number
    For Thunderbird: Open Help > About Thunderbird, or run 'thunderbird --version' from command line, or check the executable properties. Record the full version number (e.g., 147.5).
    Affected if Thunderbird version is installed and is less than 148.0
  4. Compare against affected version range
    Compare the recorded version to 148.0. Any version number less than 148.0 (including 147.x, 146.x, earlier) falls within the affected range.
    Affected if The installed version of Firefox or Thunderbird is less than 148.0

The environment is affected if either Mozilla Firefox or Thunderbird is installed with a version number lower than 148.0.

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 148.0 or later
Fixed in 148.0
Interim mitigation

Upgrade to Firefox 148 or Thunderbird 148 to remediate this vulnerability. Organizations should inventory all installations and deploy the updates immediately.

Recommended fix High confidence

Firefox 148.0 and Thunderbird 148.0

  1. Open Firefox and navigate to Menu > Help > About Firefox to check the current version
  2. If the version is below 148.0, click 'Update to the latest version' to download and install version 148.0
  3. Alternatively, download Firefox 148.0 directly from the official Mozilla website (www.mozilla.org) and reinstall
  4. For Thunderbird: Open Thunderbird and go to Menu > Help > About Thunderbird to verify the version
  5. If below 148.0, update through the built-in updater or download Thunderbird 148.0 from www.mozilla.org
  6. Restart the application after the update completes
Caveat Major browser updates may temporarily disable some extensions or themes until compatibility is confirmed by the extension developers

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

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
3.0 hours of engineering $750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.

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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-2026-2805 in production — separate from our analysis above.

No notes yet

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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