Bug 2546178 (CVE-2026-105752)

Summary: CVE-2026-105752 vllm: vLLM: Cross-tenant information disclosure via missing cache salt in tool continuations
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: low    
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. When multi-turn requests using tool continuations are processed, the service fails to retain the cache salt parameter, causing cached data to be placed in a shared, unsalted cache namespace rather than an isolated tenant cache. An authenticated tenant with knowledge of a victim's interaction history can submit matching requests and observe token cache statistics. This vulnerability results in cross-tenant information disclosure, allowing an attacker to confirm whether specific prompts or inputs were previously processed by other users.
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Description OSIDB Bzimport 2026-10-05 22:41:35 UTC 
vLLM is an inference and serving engine for large language models. Prior to 0.30.0, Harmony tool continuations submitted through "POST /v1/responses" requests rebuild the next-turn engine input without preserving the cache_salt value, placing the continuation prefix in the global unsalted cache namespace even when the caller enabled salting. On deployments with prefix caching enabled, which is the default, an authenticated tenant who can reconstruct a victim's low-entropy post-tool history can submit the same continuation and use the cached_tokens_per_turn count to determine whether the prefix was previously processed, defeating the intended tenant isolation of salted prefix caching. This issue is fixed in version 0.30.0.