CVE-2026-73559

MEDIUM 6.5

vLLM: Completion prompt lists fan out into unbounded engine requests

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

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	CWE-400
Vendor	vllm-project
Product	vllm
Published	Aug 13, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

vllm-project / vllm

>= 0.19.0, < 0.26.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/vllm-project/vllm/security/advisories/GHSA-87x5-vmc3-756j github.com: https://github.com/vllm-project/vllm/pull/47845 github.com: https://github.com/vllm-project/vllm/commit/675f4295cdfe0d870471c2b51bfeca3a68a9569e github.com: https://github.com/vllm-project/vllm/releases/tag/v0.26.0