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FirefoxWeb browser · Mozilla

CVE-2016-5283

HIGH · 8.8 CVSS v3.0 Published 2016-09-22
Fix available
A fix is available. Upgrade to after 48.0.2 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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
Mozilla Firefox before 49.0 allows remote attackers to bypass the Same Origin Policy via a crafted fragment identifier in the SRC attribute of an IFRAME element, leading to insufficient restrictions on link-color information after a document is resized.

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

This is a Same Origin Policy bypass vulnerability in Mozilla Firefox versions prior to 49.0. Attackers can exploit a crafted fragment identifier in the SRC attribute of an IFRAME element to access restricted link-color information after a document is resized, allowing unauthorized cross-origin data exposure.

MitigationUpgrade Mozilla Firefox to version 49.0 or later to address this Same Origin Policy bypass 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:<= 48.0.2

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
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/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
    Open Firefox, click the menu button (three horizontal lines), then Help > About Firefox. The version number will be displayed.
    Affected if Version is 48.0.2 or earlier, or any version prior to 49.0
  2. Verify Firefox is the affected browser
    Confirm the browser being tested is Mozilla Firefox and not another browser such as Chrome, Edge, or Safari.
    Affected if The browser is Mozilla Firefox and version is <= 48.0.2
  3. Confirm vulnerability trigger conditions exist
    This vulnerability requires a webpage containing an IFRAME element with a specially crafted fragment identifier in the SRC attribute, followed by a document resize operation.
    Affected if A vulnerable page with the described IFRAME configuration is loaded and the document is resized, enabling the SOP bypass

If Mozilla Firefox version is 48.0.2 or earlier (any version below 49.0), the environment is affected by this Same Origin Policy bypass vulnerability.

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 48.0.2
Interim mitigation

Upgrade Mozilla Firefox to version 49.0 or later to address this Same Origin Policy bypass vulnerability.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

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-2016-5283 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