FirefoxWeb browser · Mozilla
CVE-2019-17008
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 · uneditedWhen using nested workers, a use-after-free could occur during worker destruction. This resulted in a potentially exploitable crash. This vulnerability affects Thunderbird < 68.3, Firefox ESR < 68.3, and Firefox < 71.
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 use-after-free vulnerability exists in Mozilla Firefox, Firefox ESR, and Thunderbird where nested Web Workers are not properly managed during destruction. When a worker is destroyed, a reference to the worker's object is retained after memory is freed, allowing potential exploitation through a crash.
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
< 71.0
Firefox EsrWeb browser
< 68.3< 68.3= 15.1CVSS 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:3.1/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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Mozilla productCheck which Mozilla application is installed: Firefox (firefox), Firefox ESR (firefox-esr), or Thunderbird (thunderbird). On Linux, use package manager (dpkg -l | grep -i mozilla or rpm -qa | grep -i mozilla). On Windows, check Programs and Features or the application's Help > About dialog.Affected if Any of these three products are installed (Firefox, Firefox ESR, or Thunderbird)
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Determine installed versionRun the application and go to Help > About, or use command line: firefox --version, firefox-esr --version, or thunderbird --version. On Linux packages: dpkg -l firefox firefox-esr thunderbird or rpm -q firefox firefox-esr thunderbird.Affected if Version cannot be determined or is below the fixed releases
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Compare Firefox version against affected rangeIf Firefox is installed, compare the version number to 71.0. Versions below 71.0 (such as 70.x, 69.x, etc.) are affected.Affected if Firefox version is less than 71.0
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Compare Firefox ESR version against affected rangeIf Firefox ESR is installed, compare the version number to 68.3. Versions below 68.3 are affected.Affected if Firefox ESR version is less than 68.3
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Compare Thunderbird version against affected rangeIf Thunderbird is installed, compare the version number to 68.3. Versions below 68.3 are affected.Affected if Thunderbird version is less than 68.3
User is affected if Firefox is below 71.0, or Firefox ESR/Thunderbird is below 68.3, AND the application uses nested Web Workers (the vulnerability trigger condition).
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 data68.371.0
Upgrade to Firefox 71 or later, Firefox ESR 68.3 or later, or Thunderbird 68.3 or later to resolve the use-after-free during worker destruction.
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-2019-17008 — 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-2019-17008 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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