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FirefoxWeb browser · Mozilla

CVE-2016-1946

CRITICAL · 9.8 CVSS v3.0 Published 2016-01-31
Fix available
A fix is available. Upgrade to after 43.0.4 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
The MoofParser::Metadata function in binding/MoofParser.cpp in libstagefright in Mozilla Firefox before 44.0 does not limit the size of read operations, which might allow remote attackers to cause a denial of service (integer overflow and buffer overflow) or possibly have unspecified other impact via crafted metadata.

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 vulnerability exists in the MoofParser::Metadata function in libstagefright's binding/MoofParser.cpp in Mozilla Firefox versions prior to 44.0. The function fails to properly limit the size of read operations when processing metadata, allowing an integer overflow that can trigger a buffer overflow. Remote attackers can exploit this by serving crafted media files containing malicious metadata.

MitigationUpgrade Mozilla Firefox to version 44.0 or later. Until the update is applied, avoid opening untrusted media files from unknown sources, particularly MP4/Moof files.

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:<= 43.0.4
LeapOperating system
Affected:= 42.1
OpensuseOperating system
Affected:= 13.1= 13.2

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
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. Check installed Firefox version
    Navigate to Firefox > Help > About Firefox, or run 'firefox --version' in terminal, or check the package manager (e.g., 'rpm -q firefox' or 'dpkg -l firefox')
    Affected if Version is 43.0.4 or earlier (the version number is less than 44.0)
  2. Verify libstagefright library presence
    Check for libstagefright files in the Firefox installation directory: search for 'libstagefright' files within the Firefox program directory (e.g., find /usr/lib/firefox -name '*stagefright*' 2>/dev/null)
    Affected if The libstagefright library files exist in the Firefox installation directory, indicating the vulnerable component is present
  3. Identify media handling configuration
    Check Firefox configuration: in address bar enter 'about:config', search for 'media.fragmented-mp4' or 'stagefright' related preferences
    Affected if Media parsing features for fragmented MP4 (such as 'media.fragmented-mp4.enabled' or 'media.mediasource.enabled') are set to true, enabling the vulnerable code path

If Firefox version is 43.0.4 or earlier AND the libstagefright component is present with MP4 media handling enabled, the environment is vulnerable to the buffer overflow through crafted media files.

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 43.0.4
Interim mitigation

Upgrade Mozilla Firefox to version 44.0 or later. Until the update is applied, avoid opening untrusted media files from unknown sources, particularly MP4/Moof files.

Recommended fix High confidence

Firefox 44.0 or later (preferably latest stable release)

  1. Check current Firefox version via Help > About Firefox or running 'firefox --version' in command line
  2. If version is 43.0.4 or earlier, download Firefox 44.0 or later from the official Mozilla website (www.mozilla.org)
  3. Close all Firefox instances
  4. Install the upgraded Firefox version
  5. Restart Firefox and verify the new version is installed
Caveat Minor: Some older Firefox extensions or plugins may not be compatible with the newer version; test critical extensions before production deployment

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
  • Testing4.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,360
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,176.

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-2016-1946 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