{"cve":{"cve_id":"CVE-2026-34756","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00293,"epss_percentile":0.2079,"epss_as_of":"2026-06-23","description":"vLLM is an inference and serving engine for large language models (LLMs). From 0.1.0 to before 0.19.0, a Denial of Service vulnerability exists in the vLLM OpenAI-compatible API server. Due to the lack of an upper bound validation on the n parameter in the ChatCompletionRequest and CompletionRequest Pydantic models, an unauthenticated attacker can send a single HTTP request with an astronomically large n value. This completely blocks the Python asyncio event loop and causes immediate Out-Of-Memory crashes by allocating millions of request object copies in the heap before the request even reaches the scheduling queue. This vulnerability is fixed in 0.19.0.","published_at":"2026-04-06T15:40:03.448000Z","last_modified_at":null,"cvss_v3_score":6.5,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvss_v3_severity":"MEDIUM","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-770"],"nvd_references":["https://github.com/vllm-project/vllm/security/advisories/GHSA-3mwp-wvh9-7528","https://github.com/vllm-project/vllm/pull/37952","https://github.com/vllm-project/vllm/commit/b111f8a61f100fdca08706f41f29ef3548de7380"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:29:59.926872Z"},"effective_severity":"MEDIUM","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"L","value_label":"Low"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"N","value_label":"None"},{"metric":"I","name":"Integrity","value":"N","value_label":"None"},{"metric":"A","name":"Availability","value":"H","value_label":"High"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"vllm-project","vendor_name":"vllm-project","product_slug":"vllm","product_name":"vllm","version_start":">= 0.1.0, < 0.19.0","version_start_inclusive":true,"version_end":">= 0.1.0, < 0.19.0","version_end_inclusive":true,"cpe23_uri":"cve5:vllm-project:vllm:>= 0.1.0, < 0.19.0:>= 0.1.0, < 0.19.0"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-3mwp-wvh9-7528","source_type":"VENDOR_ADVISORY","tags":["advisory"]},{"url":"https://github.com/vllm-project/vllm/pull/37952","source_type":"PATCH","tags":["patch"]},{"url":"https://github.com/vllm-project/vllm/commit/b111f8a61f100fdca08706f41f29ef3548de7380","source_type":"PATCH","tags":["patch"]}],"timeline":[{"type":"published","at":"2026-04-06T15:40:03.448000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-06-28T17:53:26.161903Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:53:26.161903Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:53:26.161903Z","label":"CVSS score revised","source":"cvelistv5"}]}