What’s Vulnerable › Vulnerabilities
CVE-2026-44428: MCP Registry: GitHub OIDC tokens replayable across registry deployments due to shared audience
- Severity: medium (CVSS 4.7 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.2% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-05-14 · updated 2026-10-26
- Weakness: CWE-918
Description
The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.6, the client-side and server-side GitHub OIDC flow is bound only to a global audience string, not to the specific registry instance being targeted. On the client side, the publisher always appends audience=mcp-registry when requesting the GitHub Actions ID token, regardless of the selected --registry URL. On the server side, the exchange endpoint validates only that same fixed audience and then derives publish permissions directly from repository_owner. As a result, a token legitimately obtained while interacting with one registry deployment remains acceptable to any other deployment that shares the same code and audience string. This vulnerability is fixed in 1.7.6.
Affected products
- modelcontextprotocol registry: before 1.7.6 — fixed in 1.7.6
How to fix
Upgrade to a fixed version: modelcontextprotocol registry 1.7.6. Check the vendor advisory for mitigations.
References
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