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FirefoxWeb browser · Mozilla

CVE-2016-5297

CRITICAL · 9.8 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to 45.5.0 / 50.0 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
An error in argument length checking in JavaScript, leading to potential integer overflows or other bounds checking issues. This vulnerability affects Thunderbird < 45.5, Firefox ESR < 45.5, and Firefox < 50.

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 flaw in JavaScript argument length validation in the SpiderMonkey engine allows integer overflow when processing arguments, potentially leading to memory corruption and arbitrary code execution. This is a bounds checking error that can be triggered through specially crafted JavaScript code.

MitigationUpgrade affected products to Firefox 50+, Firefox ESR 45.5+, or Thunderbird 45.5+ to patch the JavaScript engine vulnerability.

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:< 45.5.0< 50.0
Debian LinuxOperating system
Affected:= 8.0
ThunderbirdApplication
Affected:< 45.5.0

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:3.0/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 installed Mozilla Firefox version
    Run 'firefox --version' or check Help > About Firefox in the application menu
    Affected if The reported version is less than 45.5.0 or less than 50.0 (for versions between 45.5.0 and 49.x)
  2. Identify installed Mozilla Thunderbird version
    Run 'thunderbird --version' or check Help > About Thunderbird in the application menu
    Affected if The reported version is less than 45.5.0
  3. Check if running Debian 8.0 and using packaged Mozilla products
    Run 'cat /etc/debian_version' to confirm Debian 8.0, then check installed Firefox/Thunderbird packages with 'dpkg -l | grep -i firefox' or 'dpkg -l | grep -i thunderbird'
    Affected if Running Debian 8.0 with Firefox or Thunderbird packages installed from the Debian repository
  4. Verify SpiderMonkey JavaScript engine is in use
    The vulnerability is in the SpiderMonkey engine, which is used by default in Firefox and Thunderbird - confirm by loading 'about:support' in the browser address bar
    Affected if The browser is Firefox or Thunderbird (both use SpiderMonkey)
  5. Confirm the argument processing feature is accessible
    The flaw is triggered through JavaScript argument handling - any website can execute the malicious JavaScript code if the vulnerable engine is used
    Affected if The browser can execute JavaScript (default enabled state)

You are affected if you run Firefox with version < 45.5.0 or between 45.5.0 and 49.x, or Thunderbird with version < 45.5.0, particularly on Debian 8.0 systems.

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 45.5.0 / 50.0 or later
Fixed in 45.5.050.0
Interim mitigation

Upgrade affected products to Firefox 50+, Firefox ESR 45.5+, or Thunderbird 45.5+ to patch the JavaScript engine vulnerability.

Recommended fix High confidence

Firefox 50.0 (or latest stable); Thunderbird 45.5.0 (or later)

  1. For Firefox on any platform: Download and install Firefox 50.0 or later from mozilla.org, or use your system's package manager to update to the latest version
  2. For Thunderbird: Download and install Thunderbird 45.5.0 or later from mozilla.org, or use your system's package manager to update
  3. For Debian 8.0 systems: Run 'apt-get update && apt-get install firefox-esr thunderbird' to install the latest security updates, or 'apt-get update && apt-get upgrade' to apply all pending updates
Caveat Minor: Some legacy add-ons may be incompatible with Firefox 50+ as Mozilla changed their add-on API; Thunderbird 45.5+ maintains compatibility with Firefox ESR 45 profile format

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $910
Get the upgrade done

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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-2016-5297 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