Vulnerability · Published Oct 5, 2026 · Assigned by GitHub_M
CVE-2026-105752vLLM: Harmony tool continuations drop `cache_salt` — restoring a cross-tenant prefix-cache membership oracle
Low 3.1
In plain English
A low-severity information exposure in vllm from vllm-project. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | vllm | 0.30.0 | GHSA-935w-9g4m-p28p |
| PyPI | vllm | 0.30.0 | PYSEC-2026-4308 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| vllm-project | vllm | < 0.30.0 |
Weakness: CWE-200, CWE-524 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
References
- https://github.com/vllm-project/vllm/security/advisories/GHSA-935w-9g4m-p28p x_refsource_CONFIRM
- https://github.com/vllm-project/vllm/pull/50195 x_refsource_MISC
- https://github.com/vllm-project/vllm/pull/51818 x_refsource_MISC
- https://github.com/vllm-project/vllm/commit/6a2a2bb02b563b83f946012959fd3927984d072a x_refsource_MISC
- https://github.com/vllm-project/vllm/releases/tag/v0.30.0 x_refsource_MISC