Bug 2541900 (CVE-2026-100647)

Summary: CVE-2026-100647 vllm: vLLM: Denial of Service via unbounded cache_salt parameter
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. An unauthenticated remote attacker can cause a Denial of Service (DoS) by sending HTTP requests containing an excessively large cache_salt parameter to exposed API endpoints. Because this input lacks maximum length validation, processing the oversized data consumes excessive CPU resources on the core scheduler thread. This stalling prevents legitimate requests from being processed, resulting in high latency or complete service unavailability for concurrent users.
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Description OSIDB Bzimport 2026-09-26 13:41:36 UTC 
vLLM versions before 0.29.0 contain a denial-of-service vulnerability in the cache_salt parameter accepted on OpenAI-compatible and Anthropic API endpoints, which lacks maximum length validation and is processed on the single EngineCore scheduler thread. Unauthenticated attackers can send HTTP requests with multi-hundred-megabyte salt values that trigger expensive pickle serialization and SHA-256 hashing, stalling the scheduler thread and denying service to all concurrent requests.