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.

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable yes

Technical Impact partial

Affected Vendors & Products

Vendors Products
Vllm
  • Vllm

Configuration 1 [-]

cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:*

No data.

References
Link Providers
https://github.com/vllm-project/vllm cve-icon cve-icon cve-icon
https://github.com/vllm-project/vllm/blob/v0.29.0/vllm/distributed/kv_transfer/kv_connector/v1/nixl/base_worker.py#L2642-L2646 cve-icon cve-icon cve-icon
https://github.com/vllm-project/vllm/pull/51505 cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-94623 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-94623 cve-icon
https://www.vulncheck.com/advisories/vllm-through-0.29.0-denial-of-service-via-nixl-multi-prompt-assertion-failure cve-icon cve-icon cve-icon
History

Wed, 23 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Important

Tue, 22 Sep 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 21 Sep 2026 22:15:00 +0000

Type Values Removed Values Added
Description 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.
Title vLLM through 0.29.0 Denial of Service via NIXL Multi-Prompt Assertion Failure
First Time appeared Vllm
Vllm vllm
Weaknesses CWE-617
CPEs cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:*
Vendors & Products Vllm
Vllm vllm
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': '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'}
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-09-21T22:04:12.106Z

Updated: 2026-09-22T17:44:56.345Z

Reserved: 2026-09-21T21:42:25.636Z

Link: CVE-2026-94623

cve-icon Vulnrichment

Updated: 2026-09-22T17:23:26.331Z

cve-icon NVD

Status : Analyzed

Published: 2026-09-21T22:17:01.123

Modified: 2026-09-29T12:47:21.017

Link: CVE-2026-94623

cve-icon Redhat

Severity : Important

Publid Date: 2026-09-21T22:04:12Z

Links: CVE-2026-94623 - Bugzilla