MCP Registry: OCI ownership validation fails open on upstream rate limits, allowing attacker-controlled package claims

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Summary

CVECVE-2026-45781
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-14 21:16:48 UTC
Updated2026-05-14 21:16:48 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 3.5 LOW from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

Problem Types: CWE-636 | CWE-636 CWE-636: Not Failing Securely ('Failing Open')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.5LOWCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
3.1CNADECLARED3.5LOWCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Modelcontextprotocol Registry affected < 1.7.9 Not specified

References

ReferenceSourceLinkTags
github.com/modelcontextprotocol/registry/security/advisories/GHSA-2v5f-5... [email protected] github.com
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