vLLM : DoS via unvalidated mm_processor_kwargs in multimodal image processors (Isaac, InternVL, H2OVL, etc.)

## Summary API clients can supply arbitrary `mm_processor_kwargs` per request. vLLM forwards these values through the multimodal rendering and processing pipeline to Hugging Face and custom image/video processor constructors and calls. Resource-sensitive values such as image size, patch size, patch count, crop count, or frame count can therefore be controlled by a remote client. For processors that upscale inputs, a single request can force an allocation large enough to terminate the API server or worker with an out-of-memory condition. ## Affected Components The per-request field was introduced in commit `041e29471671a3d43afedb6a749421d56ef4d3e7` and first shipped in v0.7.3. The generic forwarding path remains present in current `main`. The Isaac path is a concrete high-amplification example: - `ChatCompletionRequest.mm_processor_kwargs` - `OnlineRenderer` request extras - `MMProcessorInputs.hf_processor_mm_kwargs` - `BaseMultiModalProcessor.info.get_hf_processor(**hf_processor_mm_kwargs)` - `IsaacProcessingInfo.get_image_processor(**kwargs)` - `IsaacImageProcessor(**kwargs)` - `process_vision_for_patches()` Equivalent constructor forwarding exists in InternVL-derived processors, H2OVL, Step3VL, NemotronVL, and other multimodal processors. The issue is at the shared remote-input boundary and is not limited to a fixed model list. ## Impact - **Availability:** one request can exhaust CPU or GPU memory and terminate a shared service process. - **Scope:** all users of the affected service instance lose availability. - **Authentication:** vLLM's API key is optional, so deployments without an external authentication layer are remotely reachable without privileges. ## Remediation Reject non-empty per-request `mm_processor_kwargs` at every API-server request schema by default. Operators serving only trusted clients can explicitly opt in to the existing override behavior. Server-level `--mm-processor-kwargs` and offline `LLM` overrides remain available. This shared boundary covers current and future multimodal processors instead of maintaining a model-specific list or a denylist that can miss custom processor arguments. A patch for this was merged here: https://github.com/vllm-project/vllm/pull/58830

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Severity from

GitHub (reviewed advisory)

Weakness

CWE-400

Also known as

CVE-2026-114055

• github.com/vllm-project/vllm/security/advisories/GHSA-gx7p-2j49-hfq4
• nvd.nist.gov/vuln/detail/CVE-2026-114055
• github.com/vllm-project/vllm/pull/58830
• github.com/vllm-project/vllm/commit/31f2e70cd3e403aaa471fb7fe3d33a7207aaf3cc
• github.com/vllm-project/vllm
• github.com/vllm-project/vllm/releases/tag/v0.31.0
• www.vulncheck.com/advisories/vllm-0.7.3-before-0.31.0-dos-via-unvalidated-mm-processor-kwargs