Mark3labs mcp-go before v1.2.1 contains an improper validation vulnerability in OAuthHandler.fetchServerMetadata that allows malicious MCP servers to obtain tokens for other resources by declaring arbitrary resources in well-known metadata. Attackers can declare a different MCP server as the RFC 8707 resource indicator, causing the authorization server to mint tokens the attacker replays against that resource.
Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 05 Nov 2026 21:15:00 +0000
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Mark3labs
Mark3labs mcp-go |
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Mark3labs
Mark3labs mcp-go |
Thu, 05 Nov 2026 19:00:00 +0000
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| Description | Mark3labs mcp-go before v1.2.1 contains an improper validation vulnerability in OAuthHandler.fetchServerMetadata that allows malicious MCP servers to obtain tokens for other resources by declaring arbitrary resources in well-known metadata. Attackers can declare a different MCP server as the RFC 8707 resource indicator, causing the authorization server to mint tokens the attacker replays against that resource. | |
| Title | mcp-go before v1.2.1 Origin Validation Error via Unvalidated Well-Known Protected Resource Metadata | |
| Weaknesses | CWE-346 | |
| References |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: VulnCheck
Published:
Updated: 2026-11-05T21:01:52.297Z
Reserved: 2026-11-05T18:19:12.668Z
Link: CVE-2026-123272
No data.
Status : Deferred
Published: 2026-11-05T19:17:20.713
Modified: 2026-11-05T21:18:45.960
Link: CVE-2026-123272
No data.
OpenCVE Enrichment
Updated: 2026-11-05T21:00:19Z
Weaknesses