Vulnerability in Vllm
CVE-2026-94623
vLLM through 0.29.0 contains a denial of service vulnerability in the NIXL connector's prefix caching implementation that fails to properly validate block counts across multi-prompt completion requests in prefill/decode disaggregated deployments. Attackers can trigger an assertion failure in NixlBaseConnectorWorker._apply_prefix_caching by submitting completion requests with multiple prompts of varying lengths, causing the decode worker to terminate and become unavailable until restarted.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (50.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
Weakness classification (CWE)
References
- github.com/vllm-project/vllm (Product, product)
- github.com/vllm-project/vllm/blob/v0.29.0/vllm/distributed/kv_transfer/kv_conne… (Product, technical-description)
- github.com/vllm-project/vllm/pull/51505 (issue-tracking, Patch, patch, Issue Tracking)
- www.vulncheck.com/advisories/vllm-through-0.29.0-denial-of-service-via-nixl-mul… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-94623?
- CVE-2026-94623 is a high-severity vulnerability in Vllm, classified under Reachable Assertion. CVSS score: 7.5/10. Published 2026-09-21.
- How severe is CVE-2026-94623?
- High severity. CVSS v3 base score is 7.5 out of 10.