What’s Vulnerable › Vulnerabilities

CVE-2026-105752: vLLM: Harmony tool continuations drop `cache_salt` — restoring a cross-tenant prefix-cache membership oracle

• Severity: low (CVSS 3.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-05 · updated 2026-10-08
• Weakness: CWE-200

Description

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.

Affected products

• vllm-project vllm: before 0.30.0 — fixed in 0.30.0

How to fix

Upgrade to a fixed version: vllm-project vllm 0.30.0. Check the vendor advisory for mitigations.

References

• https://github.com/vllm-project/vllm/commit/6a2a2bb02b563b83f946012959fd3927984d072a
• https://github.com/vllm-project/vllm/pull/50195
• https://github.com/vllm-project/vllm/pull/51818
• https://github.com/vllm-project/vllm/releases/tag/v0.30.0
• https://github.com/vllm-project/vllm/security/advisories/GHSA-935w-9g4m-p28p

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