CVE-2026-12821
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 vulnerability was determined in FlowiseAI Flowise up to 3.1.2. The impacted element is an unknown function of the file packages/components/nodes/documentloaders/S3/S3.ts of the component S3 Document Loader. Executing a manipulation can lead to path traversal. It is possible to launch the attack remotely. The vendor was contacted early about this disclosure but did not respond in any way.
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 · moderate confidenceA path traversal vulnerability exists in the S3 Document Loader component of FlowiseAI Flowise (versions up to 3.1.2). The vulnerability resides in packages/components/nodes/documentloaders/S3/S3.ts, where insufficient input validation on file paths allows attackers to access files outside the intended S3 bucket scope. The CVSS 6.3 indicates a network-exploitable flaw requiring no authentication.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
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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Check installed Flowise versionRun 'npm list flowise' or check package.json for the Flowise version. Alternatively, access the Flowise UI and look for the version number in the footer or about section.Affected if Version is 3.1.2 or lower (including any 1.x or 2.x release up to 3.1.2)
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Identify if S3 Document Loader is in useSearch Flowise installation directories for the S3 loader component. Look for files under packages/components/nodes/documentloaders/S3/ directory, or check Flowise chatflows for nodes named 'S3 Document Loader' or 'S3' in the document loader category.Affected if S3 Document Loader component is present or configured in any chatflow
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Verify the vulnerable file existsCheck for the presence of packages/components/nodes/documentloaders/S3/S3.ts in the Flowise installation directory. On Linux, this might be found under /opt/flowise or the application root where Flowise was installed.Affected if The file S3.ts exists in the documentloaders/S3 path
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Check for S3 bucket configuration exposureReview any Flowise configuration files, environment variables, or chatflow JSON definitions for S3-related settings (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, S3_BUCKET_NAME, or S3 configurations in node settings).Affected if S3 credentials or bucket configurations are defined in Flowise environment or chatflow settings
A user is affected if they run Flowise version 3.1.2 or lower AND have the S3 Document Loader component available or configured in their environment, as only then can the path traversal in S3.ts be exploited.
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 dataImplement strict path validation and sanitization in the S3 Document Loader to prevent path traversal sequences (../). Validate that all file paths resolve within expected boundaries before processing.
- Consultation3.0 h
- Implementation6.0 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 $3,984.
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Free · runs locallyCheck whether your project pulls in CVE-2026-12821 — 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-2026-12821 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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- Version or environment caveats, and links to real fixes
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