CVE-2025-66414Network attack vector

Unauthorized tool and resource access via DNS rebinding

Published Dec 2, 2025 · Updated Dec 2, 2025

DNS rebinding in MCP TypeScript SDK before 1.24.0 allows remote attackers to invoke tools or access resources through a local server. The HTTP server transports accept requests without default Host-header validation, letting a rebound attacker-controlled domain address the loopback service. Exploitation requires a user to visit a malicious website while an unauthenticated Streamable HTTP or SSE server listens on localhost without rebinding protection; stdio servers are unaffected.

CVSS severity7.6
High
EPSS probability0.51%
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 MCP TypeScript SDK before 1.24.0 allows remote attackers to invoke tools or access resources through a local server. The HTTP server transports accept requests without default Host-header validation, letting a rebound attacker-controlled domain address the loopback service. Exploitation requires a user to visit a malicious website while an unauthenticated Streamable HTTP or SSE server listens on localhost without rebinding protection; stdio servers are unaffected.

The record

CVE
CVE-2025-66414
Published
Dec 2, 2025
Updated
Dec 2, 2025
Vendor
Model Context Protocol
Product
MCP TypeScript SDK
Classifications
CWE-1188, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 2, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 2, 2025Record 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=< 1.24.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Model Context Protocol · MCP TypeScript SDKversion=< 1.24.0

Published CVSS scores

7.6GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA: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-1188Initialization of a Resource with an Insecure Default
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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