{"id":"CVE-2026-85695","aliases":["EUVD-2026-71144","GHSA-46fr-7j3v-277v"],"status":"published","title":"FastChat Unauthenticated Worker Registration SSRF and Model Spoofing","description":"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.","severity":{"version":"4.0","score":9.3,"vector":"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","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.0072,"percentile":0.54354,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-306"],"published":"2026-09-04T14:32:38Z","modified":"2026-10-28T02:30:28Z","products":[{"vendor":"lm-sys","product":"fastchat"}],"references":[{"url":"https://github.com/lm-sys/FastChat/issues/3886","tags":["issue-tracking","report"]},{"url":"https://github.com/lm-sys/FastChat","tags":["product","package"]},{"url":"https://github.com/lm-sys/FastChat/blob/v0.2.36/fastchat/serve/controller.py","tags":["technical-description","article"]},{"url":"https://www.vulncheck.com/advisories/fastchat-unauthenticated-worker-registration-ssrf-and-model-spoofing","tags":["third-party-advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-85695","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-46fr-7j3v-277v"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85695.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-85695","title":"FastChat Unauthenticated Worker Registration SSRF and Model Spoofing","description":"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.","status":"published","published":"2026-09-04T14:32:38.104Z","modified":"2026-10-01T15:21:47.088Z","cvss":[{"version":"4.0","score":9.3,"vector":"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","level":"critical","assessor":"cna"},{"version":"3.1","score":9.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L","level":"critical","assessor":"cna"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T14:19:52.410665Z"}],"euvd":[{"id":"EUVD-2026-71144","description":"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.","status":"published","published":"2026-09-04T14:32:38Z","modified":"2026-10-01T15:21:47Z","cvss":[{"version":"4.0","score":9.3,"vector":"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","level":"critical"}],"updated_at":"2026-11-02T17:27:44.672309Z"}],"ghsa":[{"id":"GHSA-46fr-7j3v-277v","title":"FastChat contains an authentication bypass vulnerability in the /register_worker endpoint that...","description":"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.","status":"published","published":"2026-09-04T15:36:16Z","modified":"2026-09-04T15:36:24Z","cvss":[{"version":"4.0","score":9.3,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"critical"},{"version":"3.1","score":9.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L","level":"critical"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T15:11:22.550434Z"}],"nvd":[{"id":"CVE-2026-85695","description":"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.","status":"published","published":"2026-09-04T15:17:47.69Z","modified":"2026-09-10T15:53:23.707Z","cvss":[{"version":"4.0","score":9.3,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"critical","assessor":"secondary"},{"version":"3.1","score":9.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L","level":"critical","assessor":"primary"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T14:12:43.737972Z"}],"osv":[{"id":"CVE-2026-85695","title":"FastChat Unauthenticated Worker Registration SSRF and Model Spoofing","description":"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.","status":"published","published":"2026-09-04T14:32:38.104Z","modified":"2026-10-28T02:30:28.210405354Z","cvss":[{"version":"4.0","score":9.3,"vector":"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","level":"critical"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T15:45:18.825071Z"}]}}