vllm-project vLLM up to 0.25.x Derender /v1/completions/derender tokenizer.decode resource consumption

Summaryinfo

A vulnerability has been found in vllm-project vLLM up to 0.25.x and classified as problematic. Affected is the function tokenizer.decode of the file /v1/completions/derender of the component Derender. Performing a manipulation results in resource consumption. This vulnerability is identified as CVE-2026-71486. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as problematic has been found in vllm-project vLLM up to 0.25.x. This affects the function tokenizer.decode of the file /v1/completions/derender of the component Derender. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-71486 since 08/06/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 0.26.0 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• vllm-project

Name

• vLLM

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25

Website

• Product: https://github.com/vllm-project/vllm/

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