vLLM: Harmony tool continuations drop `cache_salt` — restoring a cross-tenant prefix-cache membership oracle (vllm-project vllm)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.22 % · percentile 12 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
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.
Weaknesses (CWE)
- CWE-200 — Exposure of Sensitive Information to an Unauthorized Actor
- CWE-524 — Use of Cache Containing Sensitive Information
References
- https://github.com/vllm-project/vllm/security/advisories/GHSA-935w-9g4m-p28p
- https://github.com/vllm-project/vllm/pull/50195
- https://github.com/vllm-project/vllm/pull/51818
- https://github.com/vllm-project/vllm/commit/6a2a2bb02b563b83f946012959fd3927984d072a
- https://github.com/vllm-project/vllm/releases/tag/v0.30.0
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | LOW 3.1 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N | GitHub_M |
| CVSS 3.1 | LOW 3.1 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-935w-9g4m-p28p — vLLM: Harmony tool continuations drop `cache_salt` — restoring a cross-tenant prefix-cache membership oracle
- PYSEC-2026-4308 — vLLM: Harmony tool continuations drop `cache_salt` — restoring a cross-tenant prefix-cache membership oracle
European references
- ENISA EUVD · EUVD-2026-92842
- GCVE · GCVE-0-2026-105752
Affected configurations (NVD CPE)
cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:*< 0.30.0
Affected products
| Product | Versions |
|---|---|
| vllm-project · vllm | affected < 0.30.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |