# CVE-2026-94623 — vllm-project vllm

> As of 2026-09-22, CVE-2026-94623 is a HIGH-severity vulnerability in vllm-project vllm, CVSS v3.1 7.5, EPSS 0.4% (38.1th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-94623 as of 2026-09-22; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-22

## What is 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.

The record classifies CVE-2026-94623 under weakness class [CWE-617](https://intel.threadlinqs.com/cwe/CWE-617). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 14 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.5 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **CVSS v4.0 base score:** 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **EPSS (FIRST):** 0.4% probability of exploitation in the next 30 days, higher than 38.1% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-21, last modified 2026-09-22

## Is CVE-2026-94623 being exploited?

It currently carries a trending score of 39 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [vllm-project](https://intel.threadlinqs.com/vendors/vllm-project): vllm

## How to fix CVE-2026-94623

No vendor patch reference has been recorded for CVE-2026-94623 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-94623

No threat campaign in the Threadlinqs corpus currently references CVE-2026-94623, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-09-23. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com — issue tracking](https://github.com/vllm-project/vllm/pull/51505)

**Technical analysis**

- [github.com — technical description](https://github.com/vllm-project/vllm/blob/v0.29.0/vllm/distributed/kv_transfer/kv_connector/v1/nixl/base_worker.py#L2642-L2646)

**Third-party advisory**

- [vulncheck.com — third party advisory](https://www.vulncheck.com/advisories/vllm-through-0.29.0-denial-of-service-via-nixl-multi-prompt-assertion-failure)

**Issue tracking and product pages**

- [github.com — product](https://github.com/vllm-project/vllm)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-94623
Full detection coverage and IOCs for threats exploiting CVE-2026-94623 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp