HIGH8.7

PYSEC-2026-4005

Quick fix

PYSEC-2026-4005 — vllm: upgrade to the fixed version with the command below.

pip install --upgrade 'vllm>=0.30.0'

Details

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.

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/vllm

Introduced in: 0Fixed in: 0.30.0

Fixpip install --upgrade 'vllm>=0.30.0'

References

https://github.com/vllm-project/vllm/blob/v0.29.0/vllm/distributed/kv_transfer/kv_connector/v1/nixl/base_worker.py#L2642-L2646[WEB]
https://www.vulncheck.com/advisories/vllm-through-0.29.0-denial-of-service-via-nixl-multi-prompt-assertion-failure[ADVISORY]
https://github.com/vllm-project/vllm/pull/51505[FIX]
https://github.com/vllm-project/vllm[PACKAGE]