CVE-2026-105757

vLLM is an inference and serving engine for large language models. Prior to 0.30.0, structured-output request failures can escape request-scoped validation and reach the EngineCore fatal-error path. A per-request backend mismatch can re-raise a grammar compilation exception, padding produced by the ngram_gpu speculative-decoding mode can pass a negative token to guidance validation, and the Rust frontend can admit empty structured-output values that the Python frontend rejects, allowing ordinary constrained-generation requests to terminate the shared engine. This issue is fixed in version 0.30.0.

• https://github.com/vllm-project/vllm/commit/c55e15a44ec4127832d4a86928a356fdd9e68dbdPatch
• https://github.com/vllm-project/vllm/pull/51450Issue Tracking
• https://github.com/vllm-project/vllm/releases/tag/v0.30.0Release Notes
• https://github.com/vllm-project/vllm/security/advisories/GHSA-85xf-c7hm-whqwMitigation