NifiApplication · Apache
CVE-2020-9487
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 Apache NiFi 1.0.0 to 1.11.4, the NiFi download token (one-time password) mechanism used a fixed cache size and did not authenticate a request to create a download token, only when attempting to use the token to access the content. An unauthenticated user could repeatedly request download tokens, preventing legitimate users from requesting download tokens.
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 confidenceApache NiFi's download token (one-time password) mechanism failed to authenticate requests to create tokens, only authenticating when the token was used to access content. Combined with a fixed cache size for tokens, an unauthenticated attacker could repeatedly request download tokens, exhausting the cache and preventing legitimate users from obtaining tokens—a denial-of-service condition.
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
NifiApplication
>= 1.0.0, <= 1.11.4CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 Apache NiFi versionRun 'nifi.sh version' or check the nifi-app.log file header for the version string, or inspect the nifi.properties file for the 'nifi.version' propertyAffected if The installed version is between 1.0.0 and 1.11.4 inclusive
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Confirm NiFi web interface is accessibleVerify the NiFi web server is running and reachable at the configured host and port (default 8080 or 8443 for HTTPS)Affected if The NiFi web interface is exposed and unauthenticated token requests can reach the server
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Verify download token endpoint is accessibleCheck if the '/nifi-api/access/token' or download token endpoints respond without requiring authentication for token generation requestsAffected if Token requests can be made without authentication credentials
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Review logs for token request patternsSearch nifi-app.log for repeated 'Generated download token' or 'Access Token' entries in short time windows, indicating potential cache exhaustion attemptsAffected if Logs show unusually high numbers of token generation requests or cache-related errors
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Check token cache configurationInspect nifi.properties for token-related cache settings; look for any 'nifi.token.cache.size' or similar configurationAffected if A fixed-size token cache is configured (default behavior in affected versions)
A user is affected if their NiFi version is 1.0.0 through 1.11.4 and the download token endpoint accepts unauthenticated requests, allowing attackers to exhaust the token cache and deny legitimate token access.
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 dataUpgrade to Apache NiFi 1.12.0 or later, which adds authentication requirements for download token requests and addresses the cache exhaustion issue.
Fix this in Nifi
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-2020-9487 — 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-2020-9487 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
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