Bug 2546185 (CVE-2026-105757)

Summary: CVE-2026-105757 vllm: vllm: Denial of Service via unhandled structured-output errors
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: alinfoot, bbrownin, dtrifiro, weaton
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in vLLM. A remote authenticated attacker can cause a Denial of Service (DoS) by submitting specially crafted structured-output requests. Due to improper exception handling around structured-output processing, certain request-level errors fail to be contained and propagate directly into the core engine. This unhandled failure triggers a fatal error that terminates the shared engine process, disrupting service for all active and subsequent users.
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Description OSIDB Bzimport 2026-10-05 23:01:35 UTC 
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.