FirefoxWeb browser · Mozilla
CVE-2016-2816
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 · uneditedMozilla Firefox before 46.0 allows remote attackers to bypass the Content Security Policy (CSP) protection mechanism via the multipart/x-mixed-replace content type.
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 confidenceMozilla Firefox before version 46.0 contains a vulnerability that allows remote attackers to bypass Content Security Policy (CSP) protections by exploiting the multipart/x-mixed-replace content type, potentially enabling execution of CSP-restricted scripts or other malicious activities.
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
<= 45.0.2CVSS 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
- None
- Integrity
- High
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
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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Determine Firefox versionOpen Firefox, click the menu button (three horizontal lines), select Help, then About Firefox. The version number will displayed.Affected if The version listed is 45.0.2 or earlier (any version below 46.0)
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Verify CSP is in useInspect web application HTTP responses using browser developer tools (Network tab) or a proxy tool. Look for Content-Security-Policy headers in responses.Affected if CSP headers are present and enforced, and the Firefox version is below 46.0
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Identify multipart/x-mixed-replace usageReview web traffic logs or proxy captures for responses with Content-Type: multipart/x-mixed-replace. This content type is commonly used for MJPEG streams or live camera feeds.Affected if The Firefox version is below 46.0 AND the environment serves or loads content with multipart/x-mixed-replace content type
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Test CSP enforcement with mixed contentLoad a page with active CSP policy in the affected Firefox version. Use the browser console and Network tab to observe if CSP-restricted resources (scripts, inline styles) load despite CSP directives.Affected if CSP directives are bypassed and restricted resources load when multipart/x-mixed-replace content is present in the page
You are affected if Mozilla Firefox version 45.0.2 or earlier is in use and your environment involves Content Security Policy protections alongside multipart/x-mixed-replace content responses.
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 to Mozilla Firefox 46.0 or later to remediate this CSP bypass vulnerability. For organizations unable to upgrade immediately, consider restricting or monitoring web content using multipart/x-mixed-replace responses at the network level.
Fix this in Firefox
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-2816 — 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-2016-2816 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
- No spam, self-promotion, credentials, or personal data