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FirefoxWeb browser · Mozilla

CVE-2019-9799

HIGH · 7.5 CVSS v3.0 Published 2019-04-26
Fix available
A fix is available. Upgrade to 66.0 or later.
See remediation →
84/100
Remediation priority · High
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
Insufficient bounds checking of data during inter-process communication might allow a compromised content process to be able to read memory from the parent process under certain conditions. This vulnerability affects Firefox < 66.

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

Insufficient bounds checking in Firefox's inter-process communication (IPC) mechanism allows a compromised content process to read arbitrary memory from the parent process. This is a memory disclosure vulnerability stemming from inadequate validation of data boundaries during IPC operations between content and parent processes.

MitigationUpgrade Firefox to version 66 or later. For enterprise environments, deploy the updated version across all endpoints via patch management and verify successful installation.

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:< 66.0

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
None
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed Firefox version
    Open Firefox and navigate to Help > About Firefox, or run 'firefox --version' from command line, or check the application file metadata
    Affected if The displayed version number is less than 66.0
  2. Confirm multi-process architecture is enabled
    Navigate to about:support in Firefox and look for 'Multiprocess Windows' - this indicates the e10s (electrolysis) IPC mechanism is active
    Affected if Multiprocess Windows shows as enabled (the vulnerability requires the multi-process architecture to be active)
  3. Verify no hotfix or interim patch has been applied
    Check about:support for 'Security Update' entries or review installed add-ons for security patches; enterprise deployments may have applied a partial mitigation
    Affected if No security update is listed and the base version remains below 66.0

If the installed Firefox version is below 66.0 and the multi-process architecture (e10s) is enabled, the environment is vulnerable to memory disclosure via IPC.

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 66.0 or later
Fixed in 66.0
Interim mitigation

Upgrade Firefox to version 66 or later. For enterprise environments, deploy the updated version across all endpoints via patch management and verify successful installation.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.

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-2019-9799 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