vLLM through 0.29.0 Denial of Service via NIXL Multi-Prompt Assertion Failure
Published Sep 21, 2026 · Updated Nov 3, 2026
Original summary
Normalized public record · Updated Nov 3, 2026
vLLM through 0.29.0 Denial of Service via NIXL Multi-Prompt Assertion Failure
Publisher and source text is retained separately from QFinch interpretation.
QFinch assessment
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.
Evidence: public source recordsAffected products
| Affected package, product or range | Fix status |
|---|---|
| Consult the referenced vendor advisory for affected versions. | Consult source advisory |
Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.
Remediation
Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.
- Confirm the affected product and reachable code path exist in your environment.
- Apply the vendor-supported patch or mitigation from the primary advisory.
- Rescan the exact deployed revision and retain verification evidence.
Evidence coverage
- SSVC priority
- MEDIUM
- Confidence
- Not available
- Aliases
- None reported
Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.
Sources and record history
- GitHub advisory ↗
- Source repository ↗
- Source repository ↗
- VulnCheck Advisory: vLLM through 0.29.0 Denial of Service via NIXL Multi-Prompt Assertion Failure ↗
Record history
Published Sep 21, 2026 · Last refreshed Nov 3, 2026