{"id":"PYSEC-2026-2025","summary":"vLLM Denial of Service via the best_of parameter","details":"A 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.","aliases":["CVE-2024-8939","GHSA-wc36-9694-f9rf"],"modified":"2026-07-07T17:48:17.622518271Z","published":"2026-07-07T14:34:41.654363Z","references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-8939"},{"type":"WEB","url":"https://github.com/vllm-project/vllm/issues/6137"},{"type":"WEB","url":"https://access.redhat.com/security/cve/CVE-2024-8939"},{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2312782"},{"type":"PACKAGE","url":"https://github.com/vllm-project/vllm"},{"type":"PACKAGE","url":"https://pypi.org/project/vllm"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-wc36-9694-f9rf"}],"affected":[{"package":{"name":"vllm","ecosystem":"PyPI","purl":"pkg:pypi/vllm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.5.0.post1"}]}],"versions":["0.0.1","0.1.0","0.1.1","0.1.2","0.1.3","0.1.4","0.1.5","0.1.6","0.1.7","0.2.0","0.2.1","0.2.1.post1","0.2.2","0.2.3","0.2.4","0.2.5","0.2.6","0.2.7","0.3.0","0.3.1","0.3.2","0.3.3","0.4.0","0.4.0.post1","0.4.1","0.4.2","0.4.3","0.5.0","0.5.0.post1"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/vllm/PYSEC-2026-2025.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}