{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "last_affected": "0.2.36"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "b21d0f780ca4472a13714262a0790f2ee1ade659"
            }
          ],
          "repo": "https://github.com/lm-sys/fastchat",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-306"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85695.json"
  },
  "details": "FastChat contains an authentication bypass vulnerability in the /register_worker endpoint that allows unauthenticated attackers to register arbitrary worker addresses and perform server-side request forgery. Attackers can register malicious workers under victim model names to intercept user prompts, images, and responses, or probe internal network ports across the worker mesh.",
  "id": "CVE-2026-85695",
  "modified": "2026-09-06T03:30:16.910034776Z",
  "published": "2026-09-04T14:32:38.104Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85695.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-85695"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/fastchat-unauthenticated-worker-registration-ssrf-and-model-spoofing"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/lm-sys/FastChat/issues/3886"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/lm-sys/FastChat"
    },
    {
      "type": "ARTICLE",
      "url": "https://github.com/lm-sys/FastChat/blob/v0.2.36/fastchat/serve/controller.py"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "FastChat Unauthenticated Worker Registration SSRF and Model Spoofing"
}