CVE-2026-59973

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Source
https://cve.org/CVERecord?id=CVE-2026-59973
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59973.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-59973
Aliases
Published
2026-09-15T15:13:40Z
Modified
2026-09-17T03:47:28Z
Severity
  • 8.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N CVSS Calculator
Summary
mcp-from-openapi: Bypass of OpenAPI external $ref SSRF fix in latest FrontMCP and mcp-from-openapi
Details

FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). From mcp-from-openapi 2.3.0 until 2.5.0 and from frontmcp and @frontmcp/adapters 1.2.1 until 1.5.0, libs/adapters/src/openapi/openapi.adapter.ts loadOpenAPISpec() forwards untrusted OpenAPI url and spec inputs and loadOptions.refResolution to OpenAPIToolGenerator.fromURL() and OpenAPIToolGenerator.fromJSON(). The external $ref guard checks parsed hostname strings without resolving addresses, pinning validated addresses, revalidating redirect targets, or normalizing IPv4-mapped IPv6. An authenticated user who can import or configure an OpenAPI specification in a hosted or multi-user deployment can use DNS-to-loopback resolution, redirect-to-loopback behavior, or IPv4-mapped IPv6 loopback forms to cause backend-origin requests to internal services. This can expose internal administrative APIs, metadata-like services, and other private network endpoints. The practical impact is lower when only a trusted local administrator can configure OpenAPI specs, and disabling external reference protocols prevents the external $ref request. This issue is fixed in mcp-from-openapi 2.5.0 and frontmcp and @frontmcp/adapters 1.5.0.

Database specific 
{
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-918"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59973.json"
}
References

Affected packages

Git / github.com/agentfront/frontmcp

Affected ranges

Type
GIT
Repo
https://github.com/agentfront/frontmcp
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
96a78eaa5c6c4bc51cced557d83d1a03344cb03d
Fixed
c1740dc4fd6a10e42f771b2c7715d2e091ec5d0e
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "1.5.0"
        }
    ],
    "source": [
        "AFFECTED_FIELD",
        "REFERENCES"
    ]
}
Type
GIT
Repo
https://github.com/agentfront/mcp-from-openapi
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
be3409cce6e97642696d4ee5a4e4e2712490b277
Fixed
a8c0ff2f6fa1c072604d9c30027d8368f11a07b4
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "2.5.0"
        }
    ],
    "source": [
        "AFFECTED_FIELD",
        "REFERENCES"
    ]
}

Affected versions

v0.*
v0.2.5
v0.3.0
v0.3.1
v0.4.0
v0.5.0
v0.5.1
v0.6.0
v0.6.1
v0.6.2
v0.6.3
v0.7.1
v0.7.2
v0.8.0
v0.8.1
v1.*
v1.5.0-rc.1
v2.*
v2.4.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59973.json"