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FirefoxWeb browser · Mozilla

CVE-2014-1551

HIGH · 10.0 CVSS v2.0 Published 2014-07-23
Fix available
A fix is available. Upgrade to after 30.0 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
Use-after-free vulnerability in the FontTableRec destructor in Mozilla Firefox before 31.0, Firefox ESR 24.x before 24.7, and Thunderbird before 24.7 on Windows allows remote attackers to execute arbitrary code via crafted use of fonts in MathML content, leading to improper handling of a DirectWrite font-face object.

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

A use-after-free vulnerability exists in the FontTableRec destructor in Mozilla Firefox (before 31.0) and Thunderbird (before 24.7) on Windows. The vulnerability is triggered by specially crafted fonts embedded in MathML content, causing improper handling of DirectWrite font-face objects and allowing remote attackers to execute arbitrary code.

MitigationApply the vendor-supplied security updates: upgrade Firefox to version 31.0 or later, Firefox ESR to 24.7 or later, or Thunderbird to 24.7 or later. Until patched, avoid viewing untrusted MathML content on affected Windows 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:<= 30.0= 24.0= 24.0.1= 24.0.2= 24.1.0= 24.1.1
Firefox EsrWeb browser
Affected:= 24.2= 24.3= 24.4= 24.5= 24.6
ThunderbirdApplication
Affected:<= 24.6= 24.0= 24.0.1= 24.1= 24.1.1= 24.2= 24.3= 24.4= 24.5

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
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/Au:N/C:C/I:C/A:C

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 the installed product
    Check if Mozilla Firefox or Thunderbird is installed. On Windows, look in Program Files for 'Mozilla Firefox' or 'Mozilla Thunderbird' folders, or check the application's executable properties.
    Affected if The product is Firefox or Thunderbird on Windows
  2. Determine the installed version
    Open Firefox or Thunderbird, go to Help > About, or check the application executable properties for the version number.
    Affected if The version matches one of the affected ranges: Firefox <= 30.0, Firefox 24.x versions, Firefox ESR 24.2-24.6, Thunderbird <= 24.6, or Thunderbird 24.x versions (specifically 24.0, 24.0.1, 24.1, 24.1.1, 24.2, 24.3, 24.4, 24.5)
  3. Confirm the operating system is Windows
    Check the operating system where the Mozilla product is running (this vulnerability affects Windows only).
    Affected if The system is running Windows
  4. Verify if MathML support is present
    Check if MathML rendering is enabled in the browser or mail client settings. In Firefox, this can be about:config and search for 'mathml' or check if MathML fonts are loaded.
    Affected if MathML support is enabled in the product (required for the exploit vector)

A user is affected if they are running a vulnerable version of Firefox or Thunderbird on Windows (version 24.x through 30.0 for Firefox, or 24.x through 24.6 for Thunderbird) with MathML support enabled, as the vulnerability requires Windows and MathML content rendering.

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 a release after 30.0
Interim mitigation

Apply the vendor-supplied security updates: upgrade Firefox to version 31.0 or later, Firefox ESR to 24.7 or later, or Thunderbird to 24.7 or later. Until patched, avoid viewing untrusted MathML content on affected Windows systems.

Recommended fix High confidence

Firefox 31.0 or later; Firefox ESR 24.7 or later; Thunderbird 24.7 or later

  1. 1. Back up any important data and bookmarks in the current Firefox, Firefox ESR, or Thunderbird installation
  2. 2. Download the fixed version: Firefox 31.0 or later from mozilla.org
  3. 3. For Firefox ESR users, download version 24.7 or later from mozilla.org
  4. 4. For Thunderbird users, download version 24.7 or later from mozilla.org
  5. 5. Close all instances of the affected application
  6. 6. Run the installer for the new version
  7. 7. Restart the application and verify it launches successfully
  8. 8. Confirm the version by checking Help > About (Firefox) or Help > About Thunderbird
Caveat Upgrading to newer major versions (e.g., from Firefox 24.x to 31.0) may cause compatibility issues with older extensions or add-ons; consider checking extension compatibility before upgrading in enterprise environments

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
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

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Scan for this in your stack

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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-2014-1551 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