Bug 2567474 (CVE-2026-123272) - CVE-2026-123272 github.com/mark3labs/mcp-go: mcp-go: Unauthorized access via improper OAuth metadata validation
Summary: CVE-2026-123272 github.com/mark3labs/mcp-go: mcp-go: Unauthorized access via ...
Keywords:
Status: NEW
Alias: CVE-2026-123272
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-11-05 22:00 UTC by OSIDB Bzimport
Modified: 2026-11-05 22:29 UTC (History)
1 user (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-11-05 22:00:48 UTC 
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.
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