Medplum is a developer platform that enables development of healthcare apps. Prior to version 5.1.6, the external identity provider callback at GET /auth/external accepts attacker-controlled redirect URIs that only need to start with a registered client redirect URI, rather than matching exactly. After a successful external IdP login, the server appends Medplum login and code values to that attacker-supplied URL and issues a redirect. Because the external login request state is serialized as raw JSON and later trusted by the callback, an attacker who can tamper with state.redirectUri can cause Medplum to redirect authorization artifacts to an attacker-controlled endpoint. When the registered redirect URI is a bare origin or another prefix that can be extended into a different hostname, this becomes a cross-origin authorization code leak. This issue has been patched in version 5.1.6.
Metrics
Affected Vendors & Products
Advisories
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-m44r-7c5h-m6mj | Medplum: Improper Validation of Redirect URI in External Auth Callback allows Authorization Code Leakage |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 03 Sep 2026 20:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Medplum
Medplum medplum |
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| Vendors & Products |
Medplum
Medplum medplum |
Thu, 03 Sep 2026 19:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Medplum is a developer platform that enables development of healthcare apps. Prior to version 5.1.6, the external identity provider callback at GET /auth/external accepts attacker-controlled redirect URIs that only need to start with a registered client redirect URI, rather than matching exactly. After a successful external IdP login, the server appends Medplum login and code values to that attacker-supplied URL and issues a redirect. Because the external login request state is serialized as raw JSON and later trusted by the callback, an attacker who can tamper with state.redirectUri can cause Medplum to redirect authorization artifacts to an attacker-controlled endpoint. When the registered redirect URI is a bare origin or another prefix that can be extended into a different hostname, this becomes a cross-origin authorization code leak. This issue has been patched in version 5.1.6. | |
| Title | Medplum - Improper Validation of Redirect URI in External Auth Callback allows Authorization Code Leakage | |
| Weaknesses | CWE-345 CWE-601 |
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| References |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-09-03T19:04:30.358Z
Reserved: 2026-06-10T16:43:31.242Z
Link: CVE-2026-53728
No data.
Status : Received
Published: 2026-09-03T20:17:21.643
Modified: 2026-09-03T20:17:21.643
Link: CVE-2026-53728
No data.
OpenCVE Enrichment
Updated: 2026-09-03T20:30:10Z
Github GHSA