CVE-2025-62426
Medium · 6.5vLLM vulnerable to DoS via large Chat Completion or Tokenization requests with specially crafted `chat_template_kwargs`
CVSS
6.5
EPSS
0.5%
Published
Nov 20, 2025
CISA due date
—
The record
The /v1/chat/completions and /tokenize endpoints allow a `chat_template_kwargs` request parameter that is used in the code before it is properly validated against the chat template. With the right `chat_template_kwargs` parameters, it is possible to block processing of the API server for long periods of time, delaying all other requests
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| PyPI | vllm | 0.5.5 | 0.11.1 |
| Chainguard | tritonserver-backend-vllm-cuda-12.9 | 0 | 25.9.0_git20251112-r1 |
| Chainguard | tritonserver-backend-vllm-meta-cuda-12.9 | 0 | 25.9.0_git20251112-r1 |
| pypi | vllm | 0.5.5 | No fix |
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