n8n Data-Table Upload Quota Bypass Leading to Disk Exhaustion
First seen Jul 23, 2026 · Updated Jul 23, 2026
An authenticated n8n user can repeatedly abuse the data-table file upload endpoint to bypass per-request quota checks, causing temporary files to accumulate on disk faster than cleanup can remove them. This can exhaust host disk space, leading to a denial-of-service condition affecting the n8n instance and potentially other services on the same host. This is a genuine, moderate-severity resource exhaustion flaw rather than a novel agentic-AI attack, but it is directly relevant to n8n's growing role as an orchestration layer for AI agent workflows.
Technical Analysis
The vulnerability stems from a quota check that only evaluates the size of the current upload request without accounting for previously written files still sitting in the shared temporary upload directory. An authenticated user (or an automated agent/workflow with upload credentials) can issue repeated upload requests, each individually passing the per-request size check, causing unbounded accumulation of temp files until the periodic cleanup job runs. Since n8n is frequently used as a backend orchestrator for AI agents and automated pipelines, an agent with legitimate but limited privileges (or a compromised/malicious workflow node) could exploit this to degrade or crash the host, impacting all workflows and any dependent agent operations. The entry point is the data-table upload API; the impact crosses from a single tool endpoint to full host-level resource denial, affecting shared infrastructure.
Affected Systems
n8n
Detection Signatures
- Repeated POST requests to the data-table file upload endpoint from a single authenticated user in short time windows
- Rapid growth of file count/size in n8n temporary upload directory without corresponding workflow completion
- Disk usage alerts correlating with n8n temp directory growth
- Upload request patterns just under uploadMaxFileSize threshold repeated many times in succession
Remediation Steps
- 1
Upgrade n8n
Update to the patched n8n version once released (fixing versions above 2.28.0 / 1.123.58 lines) to remediate the quota accounting flaw.
- 2
Restrict upload access
Limit n8n instance access to fully trusted, authenticated users only until patched.
- 3
Lower upload size limits
Set uploadMaxFileSize to a conservative value to reduce the rate at which temp storage can be consumed.
- 4
Monitor disk usage
Add alerting on disk usage in the n8n temporary upload directory to detect abnormal accumulation early.
- 5
Increase cleanup frequency
If configurable, reduce the interval of the periodic temp-file cleanup job to shrink the exploitation window.
CVE / Advisory IDs
Industries Most Exposed
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