OAuth client secret disclosure via dynamic registration
Published Sep 3, 2026 · Updated Sep 4, 2026
Information disclosure in Medplum 4.1.10 through 5.1.6 allows remote attackers to retrieve configured OAuth client secrets. The /oauth2/register handler returns an existing defaultOAuthClients entry, including client_secret, when an unauthenticated request supplies its matching redirect_uri. Exposure requires self-hosting, dynamic client registration, a secret-bearing default client, knowledge of its redirect URI, and use of that client in an authorization flow.
Summary
What happened
Information disclosure in Medplum 4.1.10 through 5.1.6 allows remote attackers to retrieve configured OAuth client secrets. The /oauth2/register handler returns an existing defaultOAuthClients entry, including client_secret, when an unauthenticated request supplies its matching redirect_uri. Exposure requires self-hosting, dynamic client registration, a secret-bearing default client, knowledge of its redirect URI, and use of that client in an authorization flow.
The record
- CVE
- CVE-2026-44506
- Published
- Sep 3, 2026
- Updated
- Sep 4, 2026
- Vendor
- Medplum
- Product
- Medplum
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 3, 2026CVE publishedPublication date reported by the CVE source.
- Sep 4, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 4.1.10, < 5.1.7
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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Your stack
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