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FirefoxWeb browser · Mozilla

CVE-2016-1963

HIGH · 7.4 CVSS v3.0 Published 2016-03-13
Fix available
A fix is available. Upgrade to after 44.0.2 or later.
See remediation →
79/100
Remediation priority · High
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 FileReader class in Mozilla Firefox before 45.0 allows local users to gain privileges or cause a denial of service (memory corruption) by changing a file during a FileReader API read operation.

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

A race condition in the FileReader class in Mozilla Firefox before version 45.0 allows a local user to modify a file while a FileReader API read operation is in progress, potentially leading to privilege escalation or memory corruption causing denial of service.

MitigationUpgrade Mozilla Firefox to version 45.0 or later to remediate this 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:<= 44.0.2

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
Local
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:L/AC:H/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. Confirm Firefox is installed
    Check for Firefox executable in typical locations: Windows typically at C:\Program Files\Mozilla Firefox\firefox.exe, macOS at /Applications/Firefox.app, Linux at /usr/bin/firefox. On any OS, you can also try running 'firefox --version' from command line or check system programs list.
    Affected if Firefox is not installed on the system
  2. Determine installed Firefox version
    Open Firefox browser and navigate to 'about:support' in the address bar, or go to Help menu and select About Firefox. Note the version number shown on the page.
    Affected if Cannot determine version or Firefox fails to open
  3. Compare version to affected range
    Take the version number from the About page (for example, 44.0.2, 44.0, 43.0) and compare it numerically against 44.0.2. Any version less than or equal to 44.0.2 falls within the affected range.
    Affected if Version is 44.0.2 or any version lower than 44.0.2 (such as 44.0, 43.0.1, 42.0)
  4. Verify FileReader API is accessible
    This is a built-in browser feature. The FileReader API is part of standard Web APIs in Firefox and is always available to web content. No configuration check needed - just confirm Firefox is running.
    Affected if Firefox is running and is version 44.0.2 or lower

User is affected if Firefox is installed and the installed version is 44.0.2 or any earlier version.

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.

From vendor data
Upgrade available Upgrade to a release after 44.0.2
Interim mitigation

Upgrade Mozilla Firefox to version 45.0 or later to remediate this vulnerability.

Fix this in Firefox Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

Scan for this in your stack

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dbcve dependency scanner

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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-2016-1963 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