Summary
The java-sdk contains a DNS rebinding vulnerability. This vulnerability allows an attacker to access a locally or network-private java-sdk MCP server via a victims browser that is either local, or network adjacent.
This allows an attacker to make any tool call to the server as if they were a locally running MCP connected AI agent.
Details
Prior to 1.0.0 no Origin header validation was occurring, in violation of the MCP specification. Base Protocol > Transports: 2.0.1 Security Warning:
1: Servers MUST validate the Origin header on all incoming connections to prevent DNS rebinding attacks.
When the web server serving HTTP traffic to the MCP server does not perform standard CORS checks, a DNS rebinding attack is possible.
Some default server configurations and frameworks come with embedded Origin header validation. MCP servers built using those are not vulnerable to this issue. For example, the following are NOT vulnerable:
- Spring AI
Workarounds
Users can mitigate this risk by:
- Running the MCP server behind a reverse proxy (like Nginx or HAProxy) configured to strictly validate the
HostandOriginheaders. - Using a framework that inherently enforces strict CORS and Origin validation (such as Spring AI).
Impact
Any developer connecting to a malicious website can inadvertently allow an attacker to make tool calls to local or private-network MCP servers.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-35568? CVE-2026-35568 is a high-severity security vulnerability in io.modelcontextprotocol.sdk:mcp-core (maven), affecting versions < 1.0.0. It is fixed in 1.0.0.
- Which versions of io.modelcontextprotocol.sdk:mcp-core are affected by CVE-2026-35568? io.modelcontextprotocol.sdk:mcp-core (maven) versions < 1.0.0 is affected.
- Is there a fix for CVE-2026-35568? Yes. CVE-2026-35568 is fixed in 1.0.0. Upgrade to this version or later.
- Is CVE-2026-35568 exploitable, and should I be worried? Whether CVE-2026-35568 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-35568 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-35568? Upgrade
io.modelcontextprotocol.sdk:mcp-coreto 1.0.0 or later.