MCP Registry: OCI validator skips ownership check on upstream rate limits

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-45781: 0.23% estimated exploitation activity in the next 30 days; percentile 14.32 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

OCI ownership validation fails open on upstream rate limits, allowing attacker to claim arbitrary public OCI images under their own namespace Severity: Low (re-scored post-triage; see Maintainer triage note below) Affected: modelcontextprotocol/registry main branch at commit fe0cb3b (current HEAD as of 2026-05-09). Live deployment: https://registry.modelcontextprotocol.io (per repo README). Route: GitHub private security advisory (per repo SECURITY.md). --- Title 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. Summary 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.…

Published by the source

19 May 2026, 15:39 UTC

Last modified by the source

19 May 2026, 15:39 UTC

Source last checked

26 Oct 2026, 15:22 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-2v5f-5r6w-p67r

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# Patch Next advisory brief: CVE-2026-45781

Advisory: MCP Registry: OCI validator skips ownership check on upstream rate limits
IDs: CVE-2026-45781, GHSA-2v5f-5r6w-p67r
Record: https://patchnext.com/advisories/cve-2026-45781 (revision 1, source checked 26 Oct 2026, 15:22 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/modelcontextprotocol/registry 1.7.9. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/modelcontextprotocol/registry: affected < 1.7.9; fixed in 1.7.9

## Suggested inspection (read-only)
- Go github.com/modelcontextprotocol/registry: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/modelcontextprotocol/registry.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-2v5f-5r6w-p67r (GitHub-reviewed advisory GHSA-2v5f-5r6w-p67r lists affected ranges: Go github.com/modelcontextprotocol/registry >=0 <1.7.9)

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