{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-90898", "assignerOrgId": "48a46f29-ae42-4e1d-90dd-c1676c1e5e6d", "state": "PUBLISHED", "assignerShortName": "JFROG", "dateReserved": "2026-09-14T10:13:28.161Z", "datePublished": "2026-09-14T10:18:53.454Z", "dateUpdated": "2026-09-14T11:19:46.276Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "48a46f29-ae42-4e1d-90dd-c1676c1e5e6d", "shortName": "JFROG", "dateUpdated": "2026-09-14T10:18:53.454Z"}, "title": "Bifrost unauthenticated remote code execution via MCP stdio client registration", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-306", "description": "CWE-306 Missing Authentication for Critical Function", "type": "CWE"}]}, {"descriptions": [{"lang": "en", "cweId": "CWE-284", "description": "CWE-284 Improper Access Control", "type": "CWE"}]}], "affected": [{"vendor": "maximhq", "product": "Bifrost", "platforms": ["Linux", "macOS"], "collectionURL": "https://github.com/maximhq/bifrost", "packageName": "github.com/maximhq/bifrost/transports", "repo": "git://github.com/maximhq/bifrost", "modules": ["transports/bifrost-http", "core/mcp"], "programFiles": ["transports/bifrost-http/handlers/mcp.go", "transports/bifrost-http/handlers/middlewares.go"], "versions": [{"status": "affected", "version": "0", "lessThan": "2.1.0", "versionType": "semver"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "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\u00a0transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>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.</p><p>The 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).</p><p>&nbsp;transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it.</p>"}]}], "references": [{"url": "https://github.com/maximhq/bifrost/pull/6757", "name": "PR #6757: refuse unauthenticated stdio MCP registration", "tags": ["patch"]}, {"url": "https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc", "name": "Merge commit for PR #6757", "tags": ["patch"]}, {"url": "https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0", "name": "Bifrost HTTP v2.1.0 (first release containing the fix)", "tags": ["release-notes"]}, {"url": "https://github.com/maximhq/bifrost", "name": "Bifrost repository", "tags": ["product"]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV3_1": {"version": "3.1", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH", "baseSeverity": "CRITICAL", "baseScore": 9.8, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}}], "configurations": [{"lang": "en", "value": "Management API reachable and governance.auth_config.is_enabled=false, which is the documented default. Confirmed on maximhq/bifrost v1.6.3. Fixed in transports/v2.1.0 (2026-09-08). An operator who enables management authentication and keeps the admin listener off untrusted networks is not exposed to the unauthenticated form of this issue.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>Management API reachable and governance.auth_config.is_enabled=false, which is the documented default. Confirmed on maximhq/bifrost v1.6.3. Fixed in transports/v2.1.0 (2026-09-08). An operator who enables management authentication and keeps the admin listener off untrusted networks is not exposed to the unauthenticated form of this issue.</p>"}]}], "workarounds": [{"lang": "en", "value": "Set governance.auth_config.is_enabled to true, use strong administrator credentials, and firewall the management listener.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>Set governance.auth_config.is_enabled to true, use strong administrator credentials, and firewall the management listener.&nbsp;</p>"}]}], "solutions": [{"lang": "en", "value": "Upgrade Bifrost HTTP transport to 2.1.0 or later. PR #6757 returns 403 for unauthenticated stdio MCP client registration when dashboard authentication is disabled or unconfigured. Authenticated admins can still add stdio clients. The 1.6.x line through 1.6.11 and transports/v2.0.0 do not include this change.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>Upgrade Bifrost HTTP transport to 2.1.0 or later. PR #6757 returns 403 for unauthenticated stdio MCP client registration when dashboard authentication is disabled or unconfigured. Authenticated admins can still add stdio clients. The 1.6.x line through 1.6.11 and transports/v2.0.0 do not include this change.</p>"}]}], "exploits": [{"lang": "en", "value": "JFrog has a private proof of concept. An unauthenticated POST /api/mcp/client with connection_type stdio and attacker-chosen command and args starts the program in the gateway. Public exploit details are not included in this record.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>JFrog has a private proof of concept. An unauthenticated POST /api/mcp/client with connection_type stdio and attacker-chosen command and args starts the program in the gateway. Public exploit details are not included in this record.</p>"}]}], "timeline": [{"time": "2026-07-13T10:27:00.000Z", "lang": "en", "value": "Reported to the Bifrost maintainers (GHSA-86gf-xh3g-rvxq)"}, {"time": "2026-09-02T15:14:00.000Z", "lang": "en", "value": "Fix merged upstream (PR #6757)"}, {"time": "2026-09-08T15:15:00.000Z", "lang": "en", "value": "Fix first shipped in Bifrost HTTP v2.1.0"}], "credits": [{"lang": "en", "value": "Yuval Moravchick | JFrog", "type": "finder"}], "source": {"discovery": "EXTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.4"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-90898", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-09-14T11:01:44.207374Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-14T11:19:46.276Z"}}]}}

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{"affected": [{"affectedData": [{"collectionURL": "https://github.com/maximhq/bifrost", "defaultStatus": "unaffected", "modules": ["transports/bifrost-http", "core/mcp"], "packageName": "github.com/maximhq/bifrost/transports", "platforms": ["Linux", "macOS"], "product": "Bifrost", "programFiles": ["transports/bifrost-http/handlers/mcp.go", "transports/bifrost-http/handlers/middlewares.go"], "repo": "git://github.com/maximhq/bifrost", "vendor": "maximhq", "versions": [{"lessThan": "2.1.0", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "reefs@jfrog.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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\u00a0transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it."}], "id": "CVE-2026-90898", "lastModified": "2026-09-14T11:17:08.237", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "reefs@jfrog.com", "type": "Secondary"}]}, "published": "2026-09-14T11:17:08.237", "references": [{"source": "reefs@jfrog.com", "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"}], "sourceIdentifier": "reefs@jfrog.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-284"}, {"lang": "en", "value": "CWE-306"}], "source": "reefs@jfrog.com", "type": "Primary"}]}

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