CVE-2026-73559 vllm-project CVE debrief

Who should care

System administrators and security teams responsible for large language model serving engines should assess exposure, prioritize remediation, and verify system inventory to mitigate potential resource exhaustion attacks. They should also review system logs for potential exploitation attempts and ensure system updates to version 0.26.0 or later are applied.

Why it matters

CVE-2026-73559 allows an authenticated API client to exhaust system resources with a single request, affecting vLLM versions 0.19.0 to 0.25.0. Defenders should assess exposure, prioritize remediation, and verify system inventory.

• Resource exhaustion through CPU and memory consumption
• Potential denial of service through async scheduling capacity depletion
• Engine request slot and response buffering exhaustion

Technical summary

The /v1/completions endpoint in vLLM accepts an unbounded list of strings or lists of integers, which can be used to exhaust system resources. The issue is fixed in version 0.26.0. An authenticated API client can exploit this vulnerability to consume excessive CPU, memory, async scheduling capacity, engine request slots, and response buffering with a single request, affecting vLLM versions 0.19.0 to 0.25.0. Defenders should focus on updating to version 0.26.0 or later and monitoring system resource utilization closely.

Defensive priority

Medium priority for system administrators and security teams to assess and remediate

Recommended defensive actions

• Assess exposure by checking system inventory for vLLM versions 0.19.0 to 0.25.0
• Prioritize remediation for affected systems
• Verify system updates to version 0.26.0 or later
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, affected versions, and fixed version. The vulnerability allows an authenticated API client to exhaust system resources with a single request, affecting vLLM versions 0.19.0 to 0.25.0. Defenders should assess exposure, prioritize remediation, and verify system inventory. Evidence limits suggest verifying system updates to version 0.26.0 or later and reviewing system logs for potential exploitation attempts.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.