Technical impact
A remote attacker can trigger a fatal sampler exception in vLLM versions 0.22.0 through 0.23.x by sending Generate or GenerateStream requests with output_logprobs enabled and more than 128 output_candidates.token_ids. The exploit bypasses input length limits in the Rust gRPC frontend, causing the EngineCore process to terminate unexpectedly and resulting in a service crash. This vulnerability exploits improper input validation (CWE‑20) and includes an error handling flaw (CWE‑248) that leads to a denial of availability of the host model service.
Affected Systems
The affected product is vLLM from the vllm-project organization. All releases of vLLM between 0.22.0 inclusive and before 0.24.0 are vulnerable. The impacted systems run the EngineCore component exposed through the gRPC interface.
Risk and Exploitability
The CVSS score of 8.2 indicates a high severity; the EPSS score is not available, so the current probability of exploitation is unknown. The vulnerability is not listed in the CISA KEV catalog. Attackers can exploit it remotely by sending crafted gRPC requests; no local privilege escalation is required. Because the vulnerability causes a crash of the entire EngineCore, it can destabilize or take down production services that rely on vLLM.
