vulnerability / NVI-00015211 / Revision 1
Medplum: Improper Validation of Redirect URI in External Auth Callback allows Authorization Code Leakage
GitHub lists this reviewed advisory for @medplum/core. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.1 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
@medplum/core
source listed<= 5.1.5
## Summary 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. ## Technical Explanation The vulnerable flow is exposed on the unauthenticated callback route `GET /auth/external`. In `externalCallbackHandler()`, the server parses the external auth `state` and uses the decoded `clientId` and `redirectUri` after completing the IdP code exchange. If login succeeds and a client is found, the handler calls: - `getClientRedirectUri(client, body.redirectUri, true)` The third argument expli
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-m44r-7c5h-m6mj ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.