dbcve.org
FirefoxWeb browser · Mozilla

CVE-2020-12388

CRITICAL · 10.0 CVSS v3.1 Published 2020-05-26
Fix available
A fix is available. Upgrade to 68.8.0 / 76.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit 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
The Firefox content processes did not sufficiently lockdown access control which could result in a sandbox escape. *Note: this issue only affects Firefox on Windows operating systems.*. This vulnerability affects Firefox ESR < 68.8 and Firefox < 76.

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 · high confidence

Firefox content processes on Windows had insufficient access control restrictions, allowing a sandbox escape that could enable an attacker to execute arbitrary code outside the constrained content process. This is a critical sandboxing bypass in the browser's security model.

MitigationUpdate Firefox to version 76 or later (or Firefox ESR 68.8 or later) to patch the vulnerability. Organizations should deploy the update via their software distribution or patch management systems.

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:< 76.0
Firefox EsrWeb browser
Affected:< 68.8.0

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
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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. Verify Firefox is installed on Windows
    Check for Firefox installation in typical locations: %ProgramFiles%\Mozilla Firefox\firefox.exe or %ProgramFiles% (x86)\Mozilla Firefox\firefox.exe, or query the Windows registry under HKLM\SOFTWARE\Mozilla\Mozilla Firefox or HKLM\SOFTWARE\WOW6432Node\Mozilla\Mozilla Firefox
    Affected if Firefox is found installed on Windows - this vulnerability only affects Windows environments
  2. Determine the installed Firefox version
    Right-click firefox.exe, select Properties, then view the File Version field, or run 'firefox --version' from command line, or read the Version value from the registry key HKLM\SOFTWARE\Mozilla\Mozilla Firefox\CurrentVersion
    Affected if Version is displayed as a numeric value that can be compared
  3. Compare version against affected ranges
    If using Firefox Release: ensure the version is 76.0 or higher. If using Firefox ESR: ensure the version is 68.8.0 or higher. Check the product type via Help > About Firefox - 'ESR' will appear in the version string for Extended Support Release
    Affected if The installed version is below 76.0 for standard Firefox, or below 68.8.0 for Firefox ESR, indicating the vulnerability is present

A user is affected if Firefox (Release or ESR) is installed on Windows and the installed version falls below the fixed releases (76.0 or 68.8.0 respectively).

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 68.8.0 / 76.0 or later
Fixed in 68.8.076.0
Interim mitigation

Update Firefox to version 76 or later (or Firefox ESR 68.8 or later) to patch the vulnerability. Organizations should deploy the update via their software distribution or patch management systems.

Recommended fix High confidence

Firefox 76.0 (regular) or Firefox ESR 68.8.0 (ESR branch)

  1. 1. Verify current Firefox version by navigating to Menu > Help > About Firefox
  2. 2. For regular Firefox users: Download and install Firefox version 76.0 or later from the official Mozilla website (www.mozilla.org)
  3. 3. For Firefox ESR users: Download and install Firefox ESR version 68.8.0 or later from the official Mozilla website
  4. 4. Restart the browser after installation
  5. 5. Verify the update was successful by checking Menu > Help > About Firefox shows version 76.0 or higher (or ESR 68.8.0 or higher)

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-2020-12388 — 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-2020-12388 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