{"id":"CVE-2026-100651","title":"vLLM before 0.29.0 fails to enforce decoder prompt-length validation on the disaggregated serving endpoint /inference/v1/generate","summary":"vLLM before 0.29.0 fails to enforce decoder prompt-length validation on the disaggregated serving endpoint /inference/v1/generate. When the request contains a 'features' (multimodal) payload, vllm/entrypoints/serve/disagg/serving.py buil…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-400","CWE-120"],"vendor":"vllm","product":"vllm","affected":["vllm < 0.29.0"],"patched":["vllm 0.29.0"],"published":"2026-09-26","updated":"2026-10-06","sourceUpdated":"2026-10-06T19:30:25.503","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-100651","references":[{"url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-3mqx-f33v-vgp9","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/vllm-before-0.29.0-denial-of-service-via-decoder-prompt-length-bypass","label":"disclosure@vulncheck.com"},{"url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-3mqx-f33v-vgp9","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100651.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-100651"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541835"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100651"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100651"}],"tags":["nvd","cve.org","exploit-available","csaf","vex","red-hat"],"epss":0.00384,"epssPercentile":0.3231,"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-28T18:21:26.899493Z"},"ingestedAt":"2026-09-26T13:33:20.919Z","slug":"CVE-2026-100651","body":"## Overview\n\nvLLM before 0.29.0 fails to enforce decoder prompt-length validation on the disaggregated serving endpoint /inference/v1/generate. When the request contains a 'features' (multimodal) payload, vllm/entrypoints/serve/disagg/serving.py builds a multimodal EngineInput directly from the caller-supplied token_ids, and GenerateRequest.token_ids (vllm/entrypoints/serve/disagg/protocol.py) is not checked against model_config.max_model_len. For multimodal processors that report skip_prompt_length_check=True (for example Nemotron Parse, Whisper, and FireRedLID), InputProcessor._validate_prompt_len() returns immediately for both encoder and decoder prompts, so an overlong prompt becomes an EngineCoreRequest and reaches the worker input-batch copy into a fixed max_model_len-wide NumPy row. A client able to reach the endpoint on an affected model configuration can therefore submit an overlong token_ids list to trigger a worker failure and denial of service. Fixed in 0.29.0.\n\n## Affected\n\n- `vllm < 0.29.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `vllm 0.29.0`\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat AI Inference Server, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · no fix planned: Red Hat AI Inference Server, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · updated 2026-09-27 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100651.json)","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":212105,"id":"CVE-2026-100651","ts":1790623192732,"field":"exploit_available","old":"false","new":"true"}]}