Denial of Service in NocoDB via Unrestricted File Download

Executive Summary

This vulnerability exists in NocoDB software versions prior to 2026.04.4, specifically in the uploadViaURL path of the v1/v2 attachment API. An authenticated user with Editor or higher privileges could exploit the lack of enforcement of the NC_ATTACHMENT_FIELD_SIZE limit on remote content-length or the response stream. Essentially, the system did not properly check the size of files being downloaded via URL before storing them, allowing an attacker to cause the server to download arbitrarily large files.

Because the size check was missing, the server could be forced to consume excessive disk space, leading to exhaustion of storage resources and causing a denial of service condition.

This issue was fixed in version 2026.04.4 by properly enforcing the maximum allowed content length before downloading and storing files.

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Impact Analysis

The primary impact of this vulnerability is a denial of service (DoS) condition. An attacker with Editor or higher privileges can cause the server to download very large files, exhausting disk space.

This exhaustion of disk space can disrupt normal operations of the NocoDB server, potentially causing it to crash or become unresponsive, thereby affecting availability.

There is no direct impact on confidentiality or integrity according to the CVSS score, but availability is severely affected.

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Mitigation Strategies

To mitigate this vulnerability, upgrade NocoDB to version 2026.04.4 or later, where the issue with uploadViaURL path enforcing NC_ATTACHMENT_FIELD_SIZE has been fixed.

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Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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Detection Guidance

This vulnerability can be detected by monitoring for unusually large file downloads initiated via the uploadViaURL path in the v1/v2 attachment API of NocoDB prior to version 2026.04.4. Since the issue involves an authenticated user with Editor+ privileges causing large file downloads that exhaust disk space, detection involves checking for large incoming files and disk usage anomalies.

You can check disk usage on the server to detect potential exhaustion caused by this vulnerability using commands like:

• df -h # Shows disk space usage in a human-readable format
• du -sh /path/to/nocodb/storage # Shows the size of the directory where attachments are stored

To detect large file downloads via the API, you can monitor HTTP requests to the uploadViaURL endpoint and check for large content-length headers or large response sizes. For example, using network monitoring tools or logging:

• Use tcpdump or Wireshark to capture traffic to the NocoDB server and filter for requests to the uploadViaURL path.
• Check application logs for unusually large file uploads or errors related to disk space exhaustion.

Since the vulnerability requires authentication with Editor+ privileges, reviewing user activity logs for suspicious large file upload attempts can also help detect exploitation.

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