CVE-2026-35568Network attack vector

Unauthorized tool calls via missing Origin validation

Published Apr 7, 2026 · Updated Apr 7, 2026

DNS rebinding in Model Context Protocol MCP Java SDK before 1.0.0 allows remote attackers to invoke tools on local or private MCP servers. The HTTP server transport accepts browser requests without validating Origin, allowing a rebound hostname to reach loopback or private addresses. Exploitation requires a developer to visit a malicious site and a deployment without independent CORS or Origin checks; successful requests can invoke any exposed tool.

CVSS severity7.6
High
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DNS rebinding in Model Context Protocol MCP Java SDK before 1.0.0 allows remote attackers to invoke tools on local or private MCP servers. The HTTP server transport accepts browser requests without validating Origin, allowing a rebound hostname to reach loopback or private addresses. Exploitation requires a developer to visit a malicious site and a deployment without independent CORS or Origin checks; successful requests can invoke any exposed tool.

The record

CVE
CVE-2026-35568
Published
Apr 7, 2026
Updated
Apr 7, 2026
Vendor
Model Context Protocol
Product
MCP Java SDK
Classifications
CWE-346, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Model Context Protocol · MCP Java SDKversion=< 1.0.0

Published CVSS scores

7.6GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
5.7NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-346Origin Validation Error
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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