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3 vulnerabilities found for mcp-go by mark3labs

CVE-2026-123272 (GCVE-0-2026-123272)
Vulnerability from cvelistv5
Published
2026-11-05 18:45
Modified
2026-11-05 21:01
Severity ?
5.1 (Medium) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
8.0 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
CWE
  • CWE-346 - Origin Validation Error
Summary
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.
References
Impacted products
Vendor Product Version
mark3labs mcp-go Version: v0.48.0   ≤
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CVE-2026-108859 (GCVE-0-2026-108859)
Vulnerability from cvelistv5
Published
2026-10-11 13:26
Modified
2026-10-18 11:53
Severity ?
8.7 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Summary
mcp-go through 1.2.1 contains a denial of service vulnerability in StreamableHTTPServer.ServeHTTP that allows remote unauthenticated attackers to exhaust memory by sending oversized POST bodies. Attackers can send arbitrarily large or many concurrent POST requests, read fully via io.ReadAll before validation, to degrade or OOM-kill the server process.
References
Impacted products
Vendor Product Version
mark3labs mcp-go Version: 0   ≤ 1.2.1
 Create a notification for this product.
Show details on NVD website

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CVE-2026-81092 (GCVE-0-2026-81092)
Vulnerability from cvelistv5
Published
2026-08-27 14:50
Modified
2026-08-29 11:48
Severity ?
7.6 (High) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
6.8 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
CWE
  • CWE-346 - Origin Validation Error
Summary
mcp-go accepted requests on its HTTP transports without checking the Host header. StreamableHTTPServer.ServeHTTP in server/streamable_http.go and SSEServer.ServeHTTP in server/sse.go served any request arriving over a loopback connection regardless of the host it named, and the SSE transport's cross-origin default allowed any origin. A page in a browser could therefore point a name it controlled at the loopback address and reach a server listening there, invoking tools and reading resources that the server exposed on the assumption that only local software could connect. No release before 0.56.0 validated the header on either transport; 0.56.0 adds server/http_localhost.go, which rejects a loopback-bound request carrying a host that is not a loopback name, and wires it into both transports.
References
Impacted products
Vendor Product Version
mark3labs mcp-go Version: 0   ≤
Create a notification for this product.
Show details on NVD website

To clipboard 

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