Medium [CVE-2026-73559] Denial of Service via unbounded completion prompt lists
This medium-severity Red Hat Linux advisory covers CVE-2026-73559 affecting Red Hat AI Inference Server, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI).
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
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Summary
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. An authenticated API client can exploit this vulnerability by sending a single request to the /v1/completions endpoint with an excessively large list of prompts.
This unbounded input causes the vLLM server to allocate a disproportionate amount of CPU, memory, and other resources, leading to a Denial of Service (DoS) condition. This can disrupt or starve other services sharing the same vLLM instance.
This could lead to resource exhaustion, causing a denial of service for the inference engine. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-770.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 29 days ago·verify at source
Mitigation
Upgrade to a fixed release: 0.26.0. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 29 days ago·verify at source
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