Reachable assertion in vLLM - CVE-2026-115914
Published: October 21, 2026 / Updated: November 2, 2026
Vulnerability details
The vulnerability allows a remote user to cause a denial of service by crashing the entire vLLM serving instance.
The vulnerability exists due to a reachable assertion in vLLM's DeepSeek-OCR-family multimodal encoder when processing an image whose normalized pixel values sum to exactly zero. A remote user can submit a chat request containing a 1024×1024 PNG image that is half pure black and half pure white to make embed_multimodal return None, triggering an uncontained assertion failure that terminates the engine and shuts down the API server.
The trigger image must be alone in its per-step encoder batch because the zero-sum check aggregates across the entire modality batch.