vllm-project vLLM up to 0.25.x Completion Request online_renderer.py OnlineRenderer.preprocess_completion prompt resource consumption

Summaryinfo

A vulnerability categorized as problematic has been discovered in vllm-project vLLM up to 0.25.x. This affects the function OnlineRenderer.preprocess_completion of the file vllm/renderers/online_renderer.py of the component Completion Request. Such manipulation of the argument prompt leads to resource consumption. This vulnerability is referenced as CVE-2026-73559. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in vllm-project vLLM up to 0.25.x. It has been rated as problematic. Affected by this issue is the function OnlineRenderer.preprocess_completion of the file vllm/renderers/online_renderer.py of the component Completion Request. The manipulation of the argument prompt with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. CVE summarizes:

vLLM is an inference and serving engine for large language models. From 0.19.0 until 0.26.0, the /v1/completions CompletionRequest.prompt field in vllm/entrypoints/openai/completion/protocol.py accepts an unbounded list[str] or list[list[int]], prompt_to_seq() in vllm/renderers/inputs/preprocess.py and OnlineRenderer.preprocess_completion() in vllm/renderers/online_renderer.py expand every element, and vllm/entrypoints/openai/completion/serving.py creates one engine generator and response slot per prompt, allowing an authenticated API client to exhaust CPU, memory, async scheduling capacity, engine request slots, and response buffering with one request. This issue is fixed in version 0.26.0.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-73559 since 08/12/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 0.26.0 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• vllm-project

Name

• vLLM

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25

Website

• Product: https://github.com/vllm-project/vllm/

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