Bug: Critical Security Vulnerabilities and Bugs in Ollama API Integration

[Mirza-Samad-Ahmed-Baig]

Describe the issue

This report outlines critical security vulnerabilities and functional bugs found in the Ollama language model integration—specifically within the _ollama_query method in langextract/inference.py.

Identified Issues:

• Security Vulnerability – SSRF (Server-Side Request Forgery): URLs were constructed via raw string concatenation, making the system vulnerable to SSRF attacks.
• Bug – Typo in Parameter Name: The incorrect parameter num_thread was used instead of the correct num_threads.
• Bug – Incorrect Variable Used in API Call: model_url was mistakenly used in requests.post() instead of the constructed api_endpoint.
• Bug – Potential Double-Slash in URLs: Improper URL concatenation could lead to malformed paths (e.g., //api/generate).

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Expected Behavior

The Ollama API integration should:

• Properly validate URLs, allowing only http and https schemes and ensuring the presence of a hostname.
• Pass the num_threads parameter correctly to the Ollama API.
• Make requests to the appropriate /api/generate endpoint.
• Construct URLs safely to avoid double slashes.

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Actual Behavior

• SSRF vulnerabilities were possible due to unvalidated URLs.
• The thread count parameter was ignored due to a typo.
• API requests were made to the base URL instead of /api/generate.
• Malformed URLs were generated in certain configurations.

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Steps to Reproduce

1. SSRF Vulnerability:

   • Inspect _ollama_query in langextract/inference.py before the fix.
   • Pass a malicious URL (e.g., file:///etc/passwd, http://internal-service.local) via model_url.
   • Observe that the URL is accepted and processed.

2. Typo in Parameter:

   • Look for options['num_thread'] instead of options['num_threads'].
   • The Ollama API ignores the invalid parameter.

3. Incorrect API Call:

   • requests.post() uses model_url instead of api_endpoint.

4. Double-Slash URLs:

   • If model_url ends with /, concatenation without urljoin() results in malformed URLs like //api/generate.

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Additional Context

Fixes Implemented:

• Added URL validation using urllib.parse:
  • Ensures scheme is http or https.
  • Ensures hostname is present.
• Replaced num_thread with correct num_threads.
• Updated requests.post() to use api_endpoint.
• Replaced string concatenation with urljoin() for robust URL building.

These improvements resolve major security flaws and enhance API behavior.

[jvalentin-e]

I took a closer look at this and wanted to clarify a few points.

This seems like it might be over-classified as a security vulnerability. The function (which is at langextract/providers/ollama.py not langextract/inference.py) accepts a URL parameter and makes requests to it - which is the documented behavior.

Calling this 'critical' seems to suggest that any library function accepting URLs is inherently vulnerable. If a developer allows users to control the model_url parameter without validation, that seems like an application-level issue rather than a library vulnerability. While URL validation could be a nice defensive feature, this seems more like a hardening enhancement than a critical vulnerability.

The incorrect parameter num_thread was used instead of the correct num_threads.

Ollama's generate api endpoint takes the param as num_thread. I believe that the library implementation is correct and that this is not a bug.

model_url was mistakenly used in requests.post() instead of the constructed api_endpoint.

requests.post() takes the constructed api endpoint, not the raw model_url. This bug does not appear to exist.

Improper URL concatenation could lead to malformed paths (e.g., //api/generate).

Yeah, this is a potential gotcha. The documentation and all examples do show the configuration without a trailing slash, but this is exactly the sort of thing I can see myself getting wrong and spending several hours scratching my head about.