Description
The Model Context Protocol Java SDK is the official Java SDK for Model Context Protocol servers and clients. From version 0.8.0 through 0.12.0 in the io.modelcontextprotocol.sdk:mcp artifact, from 0.13.0 through 0.18.3 and 1.0.0 through 1.1.3 in io.modelcontextprotocol.sdk:mcp-core, and from mcp-core 2.0.0-M1 through 2.0.0, the Servlet-based SSE, Streamable HTTP, and Stateless server transports read an HTTP request body into memory without enforcing a maximum size. An unauthenticated remote client able to reach an affected transport can stream an arbitrarily large POST body, including with chunked transfer encoding, until the Java process exhausts its heap and becomes unavailable. Authentication, Origin or Host validation, or an upstream request-size limit can reject the request before the vulnerable read. The maintained mcp-core lines are fixed in versions 0.18.4, 1.1.4, and 2.0.1.
References8
- github.com/modelcontextprotocol/java-sdk/commit/1499df22c7023aa…
- github.com/modelcontextprotocol/java-sdk/commit/6a41dedaa062555…
- github.com/modelcontextprotocol/java-sdk/commit/8c0fdd1b1f76adb…
- github.com/modelcontextprotocol/java-sdk/commit/9e4d5fa827b6ba6…
- github.com/modelcontextprotocol/java-sdk/releases/tag/v0.18.4
- github.com/modelcontextprotocol/java-sdk/releases/tag/v1.1.4
- github.com/modelcontextprotocol/java-sdk/releases/tag/v2.0.1
- github.com/modelcontextprotocol/java-sdk/security/advisories/GH…
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 50 · as of 11 November 2026
- CWE
- CWE-770
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.