FirefoxWeb browser · Mozilla
CVE-2019-9804
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 · uneditedIn Firefox Developer Tools it is possible that pasting the result of the 'Copy as cURL' command into a command shell on macOS will cause the execution of unintended additional bash script commands if the URL was maliciously crafted. This is the result of an issue with the native version of Bash on macOS. *Note: This issue only affects macOS. Other operating systems are unaffected.*. 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 confidenceFirefox Developer Tools' 'Copy as cURL' feature does not sanitize maliciously crafted URLs, allowing embedded shell metacharacters to execute arbitrary bash commands when pasted into macOS terminals. The native macOS bash interprets characters like semicolons as command separators, enabling command injection.
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
< 66.0CVSS 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.
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Verify Firefox is installedCheck for Firefox in Applications folder (macOS) or Program Files (Windows) - look for firefox.exe or Firefox.appAffected if Firefox browser is present on the system
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Determine installed Firefox versionOpen Firefox, go to Help > About Firefox, or run: firefox --version (Linux) / check application info on macOSAffected if Version is less than 66.0 (e.g., 65.x, 64.x, etc.)
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Confirm Developer Tools accessOpen Firefox Developer Tools (F12 or Cmd+Opt+I on macOS), then open the Network tab, right-click any request and look for 'Copy as cURL' optionAffected if The Copy as cURL context menu option is available and usable
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Check for recent Developer Tools usageInspect browser profile for recent.sqlite or sessionstore.json (if accessible) for network request history, or ask user if they have recently used Developer Tools to copy requests as cURLAffected if User has recently used Developer Tools to copy network requests as cURL commands
User is affected if they have Firefox version below 66.0 installed and have used or intend to use the Developer Tools 'Copy as cURL' feature with URLs that could contain shell metacharacters.
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 · scoped66.0
Upgrade Firefox to version 66 or later. Alternatively, avoid pasting 'Copy as cURL' output directly into shells and manually review commands before execution.
Firefox 66.0
- Upgrade Firefox to version 66.0 or later
- After upgrading, verify that Developer Tools and the 'Copy as cURL' command function correctly
- Test any workflows involving copying curl commands to ensure they work as expected
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing1.0 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 $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-9804 — 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-2019-9804 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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- 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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