CVE-2026-108395 Model Context Protocol Java SDK HTTP server transports allow memory exhaustion through unbounded request bodies
Remote attackers can cause denial of service by sending unbounded HTTP request bodies to the Model Context Protocol Java SDK server transports.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-108395?
CVE-2026-108395 is a high-severity denial of service vulnerability in io.modelcontextprotocol.sdk:mcp, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-770
Which versions are affected by CVE-2026-108395?
How do I fix CVE-2026-108395?
No fix has been published for CVE-2026-108395 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-108395 being exploited?
There is no known exploitation of CVE-2026-108395 in the wild and no public exploit code.
Sources
Also known as GHSA-4x8c-5vv7-973f.