FirefoxWeb browser · Mozilla
CVE-2020-12392
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 · uneditedThe 'Copy as cURL' feature of Devtools' network tab did not properly escape the HTTP POST data of a request, which can be controlled by the website. If a user used the 'Copy as cURL' feature and pasted the command into a terminal, it could have resulted in the disclosure of local files. This vulnerability affects Firefox ESR < 68.8, Firefox < 76, and Thunderbird < 68.8.0.
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 confidenceThe 'Copy as cURL' feature in Firefox DevTools and Thunderbird did not properly escape shell characters in HTTP POST data. A malicious website could inject crafted POST data containing shell metacharacters; when a user copied the request via 'Copy as cURL' and pasted it into a terminal, arbitrary commands could execute, leading to local file disclosure.
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
< 76.0
Firefox EsrWeb browser
< 68.8.0
Ubuntu LinuxOperating system
= 16.04= 18.04= 19.10= 20.04< 68.8.0CVSS 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
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:L/AC:L/PR:L/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 checksWork through these to decide whether this CVE applies to you.
-
Check Firefox versionRun 'firefox --version' or open 'about:support' in the address bar to view the version numberAffected if The version is below 76.0 (e.g., 75.x or earlier)
-
Check Firefox ESR versionRun 'firefox --version' on an ESR installation or open 'about:support' to view the version. ESR versions include 'ESR' in the version stringAffected if The ESR version is below 68.8.0 (e.g., 68.7.0 or earlier)
-
Check Thunderbird versionRun 'thunderbird --version' or open Thunderbird and go to Help > About ThunderbirdAffected if The version is below 68.8.0 (e.g., 68.7.0 or earlier)
-
Verify the Copy as cURL feature existsOpen Firefox DevTools (F12), go to the Network tab, make a POST request, right-click the request, and look for 'Copy as cURL' in the context menuAffected if The feature is present in the DevTools context menu (vulnerable versions all have this feature without proper escaping)
You are affected if you run Firefox below 76.0, Firefox ESR below 68.8.0, or Thunderbird below 68.8.0, AND you use the 'Copy as cURL' feature in DevTools on requests from websites.
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 data68.8.076.0
Upgrade to Firefox ESR 78.x or later, Firefox 76 or later, or Thunderbird 68.8.0 or later. Users should avoid copying requests from untrusted websites into terminals until patched.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation4.0 h
- Testing3.0 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 $2,768.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-12392 — 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-2020-12392 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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