{"id":"CVE-2024-8939","aliases":["GHSA-wc36-9694-f9rf","PYSEC-2026-2025"],"title":"vLLM Denial of Service via the best_of parameter","summary":"vLLM Denial of Service via the best_of parameter","severity":"medium","cvss":6.2,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","vendor":"vllm","product":"vllm","ecosystem":"pip","affected":["vllm <= 0.5.0.post1"],"published":"2024-09-17","updated":"2026-07-07","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-wc36-9694-f9rf","references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2024-8939"},{"url":"https://github.com/vllm-project/vllm/issues/6137"},{"url":"https://access.redhat.com/security/cve/CVE-2024-8939"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2312782"},{"url":"https://github.com/vllm-project/vllm"}],"tags":["osv","pip"],"epss":0.00233,"epssPercentile":0.14457,"ingestedAt":"2026-07-08T18:25:53.597Z","slug":"CVE-2024-8939","body":"## Overview\n\nA vulnerability was found in the ilab model serve component, where improper handling of the best_of parameter in the vllm JSON web API can lead to a Denial of Service (DoS). The API used for LLM-based sentence or chat completion accepts a best_of parameter to return the best completion from several options. When this parameter is set to a large value, the API does not handle timeouts or resource exhaustion properly, allowing an attacker to cause a DoS by consuming excessive system resources. This leads to the API becoming unresponsive, preventing legitimate users from accessing the service.\n\n## Affected packages\n\n- `vllm <= 0.5.0.post1`\n\n## Remediation\n\nRefer to the advisory for the patched release.","depth":"sunlit","depthScore":34,"depthScoreParts":{"impact":34.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}