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FirefoxWeb browser · Mozilla

CVE-2015-4507

MEDIUM · 5.1 CVSS v2.0 Published 2015-09-24
Fix available
A fix is available. Upgrade to after 40.0.3 or later.
See remediation →
60/100
Remediation priority · Elevated
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 SavedStacks class in the JavaScript implementation in Mozilla Firefox before 41.0, when the Debugger API is enabled, allows remote attackers to cause a denial of service (getSlotRef assertion failure and application exit) or possibly execute arbitrary code via a crafted web site.

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

The SavedStacks class in Mozilla Firefox's JavaScript implementation contains a vulnerability that can be triggered when the Debugger API is enabled. A remote attacker can exploit this via a crafted website, causing a getSlotRef assertion failure leading to denial of service, and potentially achieving arbitrary code execution.

MitigationUpgrade Firefox to version 41.0 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:<= 40.0.3

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
High
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial

AV:N/AC:H/Au:N/C:P/I:P/A:P

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 Firefox version
    Open about:support in the Firefox address bar or run 'firefox --version' from command line. On Windows, right-click firefox.exe and view Properties > Details for version info.
    Affected if Version is 40.0.3 or lower (any version <= 40.0.3)
  2. Check if remote debugging is enabled
    Enter about:config in the address bar, then search for 'devtools.debugger.remote-enabled'. Check if this preference is set to true.
    Affected if devtools.debugger.remote-enabled is set to true (this enables the Debugger API for remote connections)
  3. Check for active debugger sessions
    Look for the developer tools panel (F12 or Ctrl+Shift+I) being open, or check for any active debugging connections in the browser. Alternatively, check if any extensions with debugger permissions (special permissions required) are installed and active.
    Affected if Developer tools are actively being used, or a debugger extension is actively consuming the Debugger API

A user is affected if their Firefox version is 40.0.3 or lower AND the Debugger API is enabled (via remote debugging being on, developer tools being used, or a debugger extension being active).

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 40.0.3
Interim mitigation

Upgrade Firefox to version 41.0 or later to remediate this vulnerability.

Fix this in Firefox Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing2.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,340
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,744.

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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-2015-4507 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