What’s Vulnerable › Vulnerabilities

CVE-2026-71486: vLLM: Derender endpoints decode caller-supplied GenerateResponse token IDs without output bounds

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-08-17 · updated 2026-10-23
• Weakness: CWE-400

Description

vLLM is an inference and serving engine for large language models. Prior to 0.26.0, the /v1/completions/derender and /v1/chat/completions/derender endpoints accept caller-supplied GenerateResponse objects whose generate_responses, choices, token_ids, prompt_logprobs, logprobs.content, top_logprobs, and routed_experts structures are processed by OnlineDerenderer and tokenizer.decode before max_model_len, max_tokens, max_num_seqs, or response-size limits are enforced, allowing an authenticated API client to consume excessive CPU and memory and produce oversized responses. This issue is fixed in version 0.26.0.

Affected products

• vllm-project vllm: before 0.26.0 — fixed in 0.26.0

How to fix

Upgrade to a fixed version: vllm-project vllm 0.26.0. Check the vendor advisory for mitigations.

References

• https://github.com/vllm-project/vllm/commit/8e61b646e2d157f9b93451fa048f9c8530c8a67b
• https://github.com/vllm-project/vllm/pull/47260
• https://github.com/vllm-project/vllm/releases/tag/v0.26.0
• https://github.com/vllm-project/vllm/security/advisories/GHSA-8737-qx52-hjff

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