{"id":"CVE-2026-90898","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-90898","generatedAt":"2026-09-20T15:57:04.682Z","title":"One unauthenticated POST /api/mcp/client is enough to run a program as the Bifrost process user (appuser on the official image). transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it.","description":"Bifrost registers MCP clients through its management API. A stdio client is a command plus args. Bifrost starts that program in the gateway the moment the client is added. No MCP handshake required.\n\n\n\nThe default is governance.auth_config.is_enabled=false. Auth off means every caller is a local admin. One unauthenticated POST /api/mcp/client is enough to run a program as the Bifrost process user (appuser on the official image).\n\n\n\n transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it.","published":"2026-09-14T11:17:08.000Z","lastModified":"2026-09-18T19:31:11.000Z","status":"Awaiting Analysis","sourceIdentifier":"reefs@jfrog.com","cvss":{"version":"3.1","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-284","CWE-306"],"affected":[],"epss":{"score":0.00343,"percentile":0.27945,"date":"2026-09-19","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.34%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://github.com/maximhq/bifrost","source":"reefs@jfrog.com"},{"url":"https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc","source":"reefs@jfrog.com"},{"url":"https://github.com/maximhq/bifrost/pull/6757","source":"reefs@jfrog.com"},{"url":"https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0","source":"reefs@jfrog.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90898","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}