{"id":"CVE-2026-85695","summary":"FastChat Unauthenticated Worker Registration SSRF and Model Spoofing","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.","modified":"2026-09-06T03:47:20.281730802Z","published":"2026-09-04T14:32:38.104Z","database_specific":{"cwe_ids":["CWE-306"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85695.json","cna_assigner":"VulnCheck"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/lm-sys/fastchat","events":[{"introduced":"0"},{"last_affected":"b21d0f780ca4472a13714262a0790f2ee1ade659"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"last_affected":"0.2.36"}]}}],"versions":["v0.2.36","v0.2.35","v0.2.34","v0.2.33","v0.2.32","v0.2.31","v0.2.30","v0.2.29","v0.2.28","v0.2.27","v0.2.26","v0.2.25","v0.2.23","v0.2.22","v0.2.21","v0.2.18","v0.2.14","v0.2.9","v0.2.5","v0.2.3","v0.2.1","v0.1.10"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-85695.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","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"}]}