CVE-2025-62426

vLLM vulnerable to DoS via large Chat Completion or Tokenization requests with specially crafted `chat_template_kwargs`

Description

vLLM is an inference and serving engine for large language models (LLMs). From version 0.5.5 to before 0.11.1, 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. This issue has been patched in version 0.11.1.

Scores

Weaknesses (CWE)

• CWE-770

Advisories

• GHSA-69j4-grxj-j64p — vLLM vulnerable to DoS via large Chat Completion or Tokenization requests with specially crafted `chat_template_kwargs`
• PYSEC-2026-2012 — vLLM vulnerable to DoS via large Chat Completion or Tokenization requests with specially crafted `chat_template_kwargs`

European references

• ENISA EUVD · EUVD-2025-198356
• GCVE · GCVE-0-2025-62426

CERT-FR advisories

• CERTFR-2025-AVI-1138 — Multiples vulnérabilités dans VMware Tanzu Platform · cert.ssi.gouv.fr
• CERTFR-2025-AVI-1057 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

• cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:* ≥ 0.5.5 < 0.11.1
• cpe:2.3:a:vllm:vllm:0.11.1:rc0:*:*:*:*:*:*
• cpe:2.3:a:vllm:vllm:0.11.1:rc1:*:*:*:*:*:*

Affected products

References

• https://github.com/vllm-project/vllm/security/advisories/GHSA-69j4-grxj-j64p
• https://github.com/vllm-project/vllm/pull/27205
• https://github.com/vllm-project/vllm/commit/3ada34f9cb4d1af763fdfa3b481862a93eb6bd2b
• https://github.com/vllm-project/vllm/blob/2a6dc67eb520ddb9c4138d8b35ed6fe6226997fb/vllm/entrypoints/chat_utils.py#L1602-L1610
• https://github.com/vllm-project/vllm/blob/2a6dc67eb520ddb9c4138d8b35ed6fe6226997fb/vllm/entrypoints/openai/serving_engine.py#L809-L814

Sources