{"id":"GHSA-95c3-6vvw-4mrq","revision":null,"records":[{"revision":"1bce0d47494e428fa70d2f70b8ee1cfd","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-44428","aliases":[],"title":"MCP Registry: GitHub OIDC tokens replayable across registry deployments due to shared audience","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.","state":0,"publishedAt":"2026-05-14T21:09:10.092+00:00","modifiedAt":"2026-05-15T14:22:18.973+00:00","affected":[{"ecosystem":"Vendor product","name":"registry","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"modelcontextprotocol\",\n                    \"product\": \"registry\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 1.7.6\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","score":2.1,"severity":"LOW"}],"references":["https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-95c3-6vvw-4mrq"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-44428","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-44428","identifiers":["CVE-2026-44428"]},"retained":false,"historicalAffected":[]},{"revision":"f10e05a6f3c94ba692a8ab05c8e4c33f","observedAt":"2026-10-28T06:07:33.888+00:00","statement":{"source":"euvd","id":"EUVD-2026-30493","aliases":["CVE-2026-44428","GHSA-95c3-6vvw-4mrq"],"title":"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 in…","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.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","score":2.1,"severity":null}],"references":["https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-95c3-6vvw-4mrq"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-30493","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"May 14, 2026, 9:09:10 PM","dateUpdated":"May 15, 2026, 2:22:18 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. 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This vulnerability is fixed in 1.7.6.","state":0,"publishedAt":"2026-05-14T22:16:44.593+00:00","modifiedAt":"2026-10-26T14:10:00.13+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","score":2.1,"severity":"LOW"},{"system":"CVSS 3.1 · nvd@nist.gov · Primary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N","score":4.7,"severity":"MEDIUM"}],"references":["https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-95c3-6vvw-4mrq"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-44428","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-918"],"productCriteria":["cpe:2.3:a:lfprojects:mcp_registry:*:*:*:*:*:*:*:*"],"sourceDates":{"published":"2026-05-14T22:16:44.593","lastModified":"2026-10-26T14:10:00.130"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. 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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.\n\n## Source-to-Sink Chain\n1. Source\n   `cmd/publisher/commands/login.go:67-105,130-135,199-224` parses the user-controlled `--registry` flag into `flags.RegistryURL`, creates a `GitHubOIDCProvider`, and calls `authProvider.GetToken(ctx)` for the chosen authentication method.\n2. Propagation\n   `cmd/publisher/auth/github-oidc.go:24-38` obtains an OIDC token and immediately exchanges it against the selected registry URL.\n   `cmd/publisher/auth/github-oidc.go:58-75` builds `exchangeURL := o.registryURL + \"/v0/auth/github-oidc\"` and posts the GitHub token to whichever registry instance was selected.\n   `cmd/publisher/auth/github-oidc.go:108-165` constructs `fullURL := requestURL + \"&audience=mcp-registry\"` and therefore requests the same audience for every registry deployment.\n3. Sink\n   `internal/api/handlers/v0/auth/github_oidc.go:75-135` validates only the shared audience value passed into `ValidateToken`.\n   `internal/api/handlers/v0/auth/github_oidc.go:254-277` calls `h.validator.ValidateToken(ctx, oidcToken, \"mcp-registry\")` and, on success, signs a new registry JWT.\n   `internal/api/handlers/v0/auth/github_oidc.go:280-296` converts `claims.RepositoryOwner` into the publish permission pattern `io.github.<owner>/*`, which is then embedded into the new registry JWT.\n\n## Exploitation Preconditions\n1. The victim uses the GitHub Actions OIDC publishing path.\n2. The victim workflow targets another registry deployment first, such as staging, self-hosted infrastructure, or an attacker-controlled registry URL.\n3. The receiving registry deployment can observe the posted OIDC token and replay it before expiry to another registry deployment running the same shared audience configuration.\n\n## Risk\nThis breaks deployment isolation between registry instances. A token issued for one registry interaction can be replayed across trust boundaries, allowing one deployment to impersonate the same GitHub owner identity on another deployment.\n\n## Impact\nAn attacker-controlled or compromised registry deployment can mint a valid registry JWT on another deployment and inherit publish permissions for the victim GitHub owner namespace. In practical terms, this enables unauthorized publication or update actions for names such as `io.github.<owner>/*` on the victim registry instance.\n\n## Remediation\n1. Replace the shared audience string with a registry-specific audience, such as a deployment-specific client ID or origin-derived identifier.\n2. Ensure the publisher requests the audience that matches the exact registry instance it is targeting, and ensure the server validates that same instance-specific value.\n3. Consider binding the exchange to additional deployment-specific claims so that a token captured by one registry cannot be replayed on another.\n4. Add regression tests that cover cross-deployment replay attempts between different registry URLs.","state":0,"publishedAt":"2026-05-08T17:06:22+00:00","modifiedAt":"2026-09-10T03:50:11.5789698+00:00","affected":[{"ecosystem":"Go","name":"github.com/modelcontextprotocol/registry","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"1.7.6"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N","score":null,"severity":null},{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"LOW"}],"references":["https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-95c3-6vvw-4mrq","https://nvd.nist.gov/vuln/detail/CVE-2026-44428","https://github.com/modelcontextprotocol/registry/pull/1229","https://github.com/modelcontextprotocol/registry/commit/3f89fc2b1fb34fd49f3c0e1b39e964a5c67b613f","https://github.com/modelcontextprotocol/registry","https://github.com/modelcontextprotocol/registry/releases/tag/v1.7.6"],"sourceUrl":"https://github.com/advisories/GHSA-95c3-6vvw-4mrq","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-95c3-6vvw-4mrq","identifiers":["GHSA-95c3-6vvw-4mrq","CVE-2026-44428","GO-2026-5273"]},"retained":false,"historicalAffected":[]},{"revision":"d601372a791e4e508ef95408a23b06b9","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GO-2026-5273","aliases":["CVE-2026-44428","GHSA-95c3-6vvw-4mrq"],"title":"MCP Registry's GitHub OIDC tokens are replayable across registry deployments due to shared audience in github.com/modelcontextprotocol/registry","description":"MCP Registry's GitHub OIDC tokens are replayable across registry deployments due to shared audience in github.com/modelcontextprotocol/registry","state":0,"publishedAt":"2026-06-25T18:43:15+00:00","modifiedAt":"2026-06-25T19:45:24.9504671+00:00","affected":[{"ecosystem":"Go","name":"github.com/modelcontextprotocol/registry","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"1.7.6"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[],"references":["https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-95c3-6vvw-4mrq","https://nvd.nist.gov/vuln/detail/CVE-2026-44428","https://github.com/modelcontextprotocol/registry/commit/3f89fc2b1fb34fd49f3c0e1b39e964a5c67b613f","https://github.com/modelcontextprotocol/registry/pull/1229","https://github.com/modelcontextprotocol/registry/releases/tag/v1.7.6"],"sourceUrl":"https://osv.dev/vulnerability/GO-2026-5273","license":"OSV · upstream source license applies","key":"osv:GO-2026-5273","identifiers":["GO-2026-5273","CVE-2026-44428","GHSA-95c3-6vvw-4mrq"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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