Vulnerability-Lookup

CVE-2026-35568 (GCVE-0-2026-35568)

Vulnerability from cvelistv5 – Published: 2026-04-07 21:06 – Updated: 2026-04-08 15:43

Title

MCP Java-SDK has a DNS Rebinding Vulnerability

Summary

MCP Java SDK is the official Java SDK for Model Context Protocol servers and clients. Prior to 1.0.0, 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. This vulnerability is fixed in 1.0.0.

Severity

7.6 (High)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-08 15:43 UTC

CWE

CWE-346 - Origin Validation Error

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/modelcontextprotocol/java-sdk/…	x_refsource_CONFIRM
https://github.com/modelcontextprotocol/java-sdk/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
modelcontextprotocol	java-sdk	Affected: < 1.0.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-35568

Vulnerability from fkie_nvd - Published: 2026-04-07 22:16 - Updated: 2026-07-24 21:10

Severity

5.7 (Medium) - CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/modelcontextprotocol/java-sdk/releases/tag/v1.0.0	Release Notes
	security-advisories@github.com	https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-8jxr-pr72-r468	Vendor Advisory

Impacted products

	Vendor	Product	Version
	lfprojects	mcp_java_sdk	*

JSON

To clipboard

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          "product": "java-sdk",
          "vendor": "modelcontextprotocol",
          "versions": [
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}

GHSA-8JXR-PR72-R468

Vulnerability from github – Published: 2026-04-07 20:13 – Updated: 2026-04-08 11:57

Summary

Java-SDK has a DNS Rebinding Vulnerability

Details

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: 1. Running the MCP server behind a reverse proxy (like Nginx or HAProxy) configured to strictly validate the Host and Origin headers. 2. Using a framework that inherently enforces strict CORS and Origin validation (such as Spring AI).

Severity

7.6 (High)


                  
                    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

Show details on source website

JSON

To clipboard

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        "name": "io.modelcontextprotocol.sdk:mcp-core"
      },
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        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-35568"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-07T20:13:32Z",
    "nvd_published_at": "2026-04-07T22:16:23Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe 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.\n\nThis allows an attacker to make any tool call to the server as if they were a locally running MCP connected AI agent.\n\n### Details\n\nPrior to 1.0.0 no Origin header validation was occurring, in violation of the MCP specification. [Base Protocol \u003e Transports: 2.0.1 Security Warning](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#security-warning):\n\n\u003e 1: Servers MUST validate the Origin header on all incoming connections to prevent DNS rebinding attacks.\n\nWhen the web server serving HTTP traffic to the MCP server does not perform standard CORS checks, a DNS rebinding attack is possible.\n\nSome 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:\n- Spring AI\n\n### Impact\n\nAny developer connecting to a malicious website can inadvertently allow an attacker to make tool calls to local or private-network MCP servers.\n\n### Workarounds\n\nUsers can mitigate this risk by:\n1. Running the MCP server behind a reverse proxy (like Nginx or HAProxy) configured to strictly validate the `Host` and `Origin` headers.\n2. Using a framework that inherently enforces strict CORS and Origin validation (such as Spring AI).",
  "id": "GHSA-8jxr-pr72-r468",
  "modified": "2026-04-08T11:57:14Z",
  "published": "2026-04-07T20:13:32Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-8jxr-pr72-r468"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35568"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/modelcontextprotocol/java-sdk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/java-sdk/releases/tag/v1.0.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Java-SDK has a DNS Rebinding Vulnerability"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-35568 (GCVE-0-2026-35568)

FKIE_CVE-2026-35568

GHSA-8JXR-PR72-R468

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