Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| mark3labs | mcp-go | ≤ 1.2.1 | — |
References
- https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/mark3labs-mcp-go-streamable-http-unbounded-body third-party-advisory
- https://github.com/mark3labs/mcp-go/blob/90d247ed8d45cbb7d71d9a95e112789b78760443/server/streamable_http.go#L405-L411 technical-description
- https://github.com/mark3labs/mcp-go product
- VulnCheck Advisory: mcp-go through 1.2.1 Denial of Service via Unbounded POST Body Buffering third-party-advisory