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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products
mark3labs:mcp-go
References 4
https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/mark3labs-mcp-go-streamable-http-unbo…
NVD
https://github.com/mark3labs/mcp-go/blob/90d247ed8d45cbb7d71d9a95e112789b787604…
NVD
https://github.com/mark3labs/mcp-go
NVD
https://www.vulncheck.com/advisories/mcp-go-through-1.2.1-denial-of-service-via…
VulnCheck Advisory: mcp-go through 1.2.1 Denial of Service via Unbounded POST Body Buffering