CVE-2026-73559

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.

• CWE-400

• https://github.com/vllm-project/vllm/commit/675f4295cdfe0d870471c2b51bfeca3a68a9569ePatch
• https://github.com/vllm-project/vllm/pull/47845Issue Tracking, Patch
• https://github.com/vllm-project/vllm/releases/tag/v0.26.0Release Notes
• https://github.com/vllm-project/vllm/security/advisories/GHSA-87x5-vmc3-756jExploit, Vendor Advisory
• https://github.com/vllm-project/vllm/security/advisories/GHSA-87x5-vmc3-756jExploit, Vendor Advisory

Published

Aug 13, 2026

Last Modified

Sep 28, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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