FirefoxWeb browser · Mozilla
CVE-2016-2837
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 · uneditedHeap-based buffer overflow in the ClearKey Content Decryption Module (CDM) in the Encrypted Media Extensions (EME) API in Mozilla Firefox before 48.0 and Firefox ESR 45.x before 45.3 might allow remote attackers to execute arbitrary code by providing a malformed video and leveraging a Gecko Media Plugin (GMP) sandbox bypass.
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 confidenceA heap-based buffer overflow exists in Mozilla Firefox's ClearKey Content Decryption Module (CDM) within the Encrypted Media Extensions (EME) API. The vulnerability is triggered when the browser processes a malformed video file, potentially allowing remote attackers to execute arbitrary code. The flaw also involves a Gecko Media Plugin (GMP) sandbox bypass, increasing the severity of potential exploitation.
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
<= 47.0.1= 45.1.0= 45.1.1= 45.2.0= 45.3.0
LinuxOperating system
= 5.0= 6= 7CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
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 checksWork through these to decide whether this CVE applies to you.
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Check if Firefox is installedRun 'firefox --version' or look for Firefox in /Applications (macOS) or Program Files (Windows)Affected if Firefox is not installed - this CVE does not apply
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Determine the installed Firefox versionOpen Firefox and navigate to 'Help' > 'About Firefox', or run 'firefox --version' from command lineAffected if Version is 47.0.1 or lower, or exactly 45.1.0, 45.1.1, 45.2.0, or 45.3.0 - proceed to next check
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Verify if Encrypted Media Extensions (EME) is enabledIn Firefox address bar, type 'about:config' and search for 'media.eme.enabled'. Check if the value is set to 'true'Affected if media.eme.enabled is true - EME is active and the vulnerable ClearKey CDM can be invoked when playing protected content
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Check for ClearKey GMP plugin presenceIn Firefox address bar, type 'about:plugins' and look for 'ClearKey' or 'Gecko Media Plugin' entry in the listAffected if ClearKey GMP plugin is present and enabled - the vulnerable code path can be triggered when processing malformed encrypted media
User is affected if Firefox version is 47.0.1 or lower, or exactly 45.1.0/45.1.1/45.2.0/45.3.0, AND EME with ClearKey is enabled or present on the system.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade Mozilla Firefox to version 48.0 or later (or ESR 45.3 or later for Extended Support Release users). This is a client-side browser vulnerability with the fix being the application of vendor-supplied patches via standard browser update mechanisms.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,232.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-2837 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2016-2837 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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
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