FirefoxWeb browser · Mozilla
CVE-2019-9820
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 · uneditedA use-after-free vulnerability can occur in the chrome event handler when it is freed while still in use. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.
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 in the chrome event handler where memory is freed while still in use, leading to a potentially exploitable crash. This is a memory corruption issue in the browser/email client core event processing.
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
< 67.0
Firefox EsrWeb browser
< 60.7< 60.7.0CVSS 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
- High
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/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.
-
Check Firefox versionRun 'firefox --version' or look in Help > About FirefoxAffected if Version is below 67.0 (for example 66.x or earlier)
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Check Firefox ESR versionRun 'firefox --version' or look in Help > About Firefox ( ESR versions include 'ESR' in the name)Affected if Version is below 60.7 (for example 60.6.x or earlier)
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Check Thunderbird versionRun 'thunderbird --version' or look in Help > About ThunderbirdAffected if Version is below 60.7.0 (for example 60.6.x or earlier)
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Verify product type on WindowsCheck Programs and Features or the application's About dialog for the exact product name and versionAffected if Any Mozilla Firefox, Firefox ESR, or Thunderbird installation matches the affected version ranges
If any installed Mozilla Firefox, Firefox ESR, or Thunderbird version is below 67.0, 60.7, or 60.7.0 respectively, the environment is affected by this use-after-free vulnerability.
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.
dbcve · scoped60.760.7.067.0
Update affected Mozilla products to patched versions: Thunderbird to >=60.7, Firefox to >=67, Firefox ESR to >=60.7.
Firefox 67.0+, Firefox ESR 60.7+, Thunderbird 60.7.0+
- 1. Close all instances of Firefox, Firefox ESR, or Thunderbird
- 2. For Firefox: Navigate to the browser's menu, select Help > About Firefox, and click 'Check for Updates' to install version 67.0 or later
- 3. For Firefox ESR: Download and install Firefox ESR 60.7 or later from the Mozilla website
- 4. For Thunderbird: Navigate to the application's menu, select Help > About Thunderbird, and click 'Check for Updates' to install version 60.7.0 or later
- 5. Verify the installed version by checking Help > About to confirm the update was successful
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-9820 — 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-2019-9820 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