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FirefoxWeb browser · Mozilla

CVE-2018-18493

CRITICAL · 9.8 CVSS v3.0 Published 2019-02-28
Fix available
A fix is available. Upgrade to 60.4.0 / 64.0 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
A buffer overflow can occur in the Skia library during buffer offset calculations with hardware accelerated canvas 2D actions due to the use of 32-bit calculations instead of 64-bit. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.4, Firefox ESR < 60.4, and Firefox < 64.

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 buffer overflow vulnerability exists in the Skia graphics library used by Firefox and Thunderbird. When performing hardware-accelerated canvas 2D operations, the code uses 32-bit integer arithmetic for buffer offset calculations instead of 64-bit, causing integer overflow that leads to out-of-bounds memory access and potentially exploitable crashes.

MitigationUpgrade to Firefox 64 or later, Firefox ESR 60.4 or later, or Thunderbird 60.4 or later to obtain the patched Skia library with 64-bit buffer offset calculations.

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:< 60.4.0< 64.0
Debian LinuxOperating system
Affected:= 8.0= 9.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 18.04= 18.10
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.6
Enterprise Linux Server EusOperating system
Affected:= 7.6
Enterprise Linux Server TusOperating system
Affected:= 7.6

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:3.0/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 if Firefox or Thunderbird is installed
    Check for executable presence: run 'which firefox' or 'which thunderbird' on Linux systems, or look for the application in the system.
    Affected if Either Firefox or Thunderbird is present on the system
  2. Determine the installed Firefox version
    Run 'firefox --version' or check the package manager (dpkg -l firefox-esr, rpm -qi firefox) depending on the distribution.
    Affected if The version returned is less than 60.4.0 or less than 64.0 (any version before 64.0 is affected if it is pre-60.4.0, but versions 60.0-60.3.x are also affected)
  3. Determine the installed Thunderbird version
    Run 'thunderbird --version' or check the package manager.
    Affected if The version is less than 60.4.0
  4. Verify if hardware-accelerated canvas 2D is enabled
    In Firefox, type 'about:support' in the address bar and look for 'GPU Process' or 'Hardware Acceleration' status. Alternatively, check for gfx.canvas.widefb.enabled or layers.acceleration.force-enabled in about:config.
    Affected if Hardware acceleration is enabled - this is required for the vulnerable code path to be exercised during canvas 2D operations

A system is affected if Firefox < 64.0 (or < 60.4.0 for ESR) or Thunderbird < 60.4.0 is installed AND hardware-accelerated canvas 2D rendering is enabled.

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 60.4.0 / 64.0 or later
Fixed in 60.4.064.0
Interim mitigation

Upgrade to Firefox 64 or later, Firefox ESR 60.4 or later, or Thunderbird 60.4 or later to obtain the patched Skia library with 64-bit buffer offset calculations.

Recommended fix High confidence

Firefox 64 or later; Firefox ESR 60.4 or later; Thunderbird 60.4 or later

  1. Upgrade Firefox to version 64 or later
  2. Upgrade Firefox ESR to version 60.4 or later
  3. Upgrade Thunderbird to version 60.4 or later
  4. For Linux distributions (Debian, Ubuntu, Enterprise Linux), apply distribution-specific security updates that include the fixed Firefox/Thunderbird packages

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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-2018-18493 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