How severe is CVE-2026-35568?

No CVSS score has been assigned to CVE-2026-35568 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-35568?

CVE-2026-35568 affects the following packages: io.modelcontextprotocol.sdk:mcp-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-35568?

Update io.modelcontextprotocol.sdk:mcp-core to 1.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-35568 is resolved across your whole dependency graph.

How do I detect CVE-2026-35568 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.modelcontextprotocol.sdk:mcp-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-35568 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-35568 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-35568 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-35568?

CVE-2026-35568 has an EPSS (Exploit Prediction Scoring System) score of 0.1%, placing it in the 4th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-35568?

CVE-2026-35568 is classified as CWE-346 (CWE-346). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-35568 published, and has it been updated?

CVE-2026-35568 was published on April 7, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

Not in CISA KEV

CVE-2026-35568 — mcp-core

CVE-2026-35568 is a CWE-346 vulnerability in io.modelcontextprotocol.sdk:mcp-core. A fix is available for io.modelcontextprotocol.sdk:mcp-core — see the affected versions and patch details below.

MCP Java-SDK has a DNS Rebinding Vulnerability

Also known asGHSA-8jxr-pr72-r468

Published

Apr 7, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-35568.

EPSS Exploitation Probability

via FIRST.org ↗

0.1%probability of exploitation in next 30 days

Lower Risk+0.01%

Lower risk than most CVEs4th percentile — riskier than 4% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

☕io.modelcontextprotocol.sdk:mcp-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

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

Impact

Any developer connecting to a malicious website can inadvertently allow an attacker to make tool calls to local or private-network MCP servers.

Workarounds

Users can mitigate this risk by:

Running the MCP server behind a reverse proxy (like Nginx or HAProxy) configured to strictly validate the Host and Origin headers.
Using a framework that inherently enforces strict CORS and Origin validation (such as Spring AI).

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.modelcontextprotocol.sdk:mcp-core`	all versions	1.0.0`io.modelcontextprotocol.sdk:mcp-core:1.0.0`

Affected Products

1 product · 1 configurations

Application

mcp java sdklfprojects

< 1.0.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.modelcontextprotocol.sdk:mcp-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.modelcontextprotocol.sdk:mcp-core to 1.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-35568 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### 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](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#security-warnin

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CVE-2026-35568 — mcp-core

Exploitation Status

No confirmed exploitation observed yet

EPSS Exploitation Probability

Real-World Exposure

Description

Summary

Details

Impact

Workarounds

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2026-35568 in your dependencies?