Vulnerability · Published May 14, 2026 · Assigned by GitHub_M
CVE-2026-45781MCP Registry: OCI ownership validation fails open on upstream rate limits, allowing attacker-controlled package claims
Low 3.5
In plain English
A low-severity security flaw in registry from modelcontextprotocol. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.9, OCI ownership validation skips label-match check when upstream OCI registry returns HTTP 429, letting any authenticated publisher bind their io.github.<user>/* namespace to OCI images they do not control. internal/validators/registries/oci.go:104-119 fails open on http.StatusTooManyRequests: when the registry's anonymous fetch to the upstream OCI registry is rate-limited, ValidateOCI returns nil and the publish is accepted without ever running the io.modelcontextprotocol.server.name label-match check at lines 122-141. That label check is the only cross-system ownership proof the registry applies to OCI packages — every other registry type (NPM, PyPI, NuGet, MCPB) treats a non-200 upstream response as a hard error. This vulnerability is fixed in 1.7.9.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/modelcontextprotocol/registry | 1.7.9 | GHSA-2v5f-5r6w-p67r |
| Go | github.com/modelcontextprotocol/registry | 1.7.9 | GO-2026-5008 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| modelcontextprotocol | registry | < 1.7.9 |
Weakness: CWE-636 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N