CVE-2026-55605Public exploitNetwork attack vector

Unauthenticated tool execution via unguarded MCP initialization

Published Jul 9, 2026 · Updated Jul 9, 2026

Missing authentication in DeepSeek MCP Server 1.4.2 through 1.7.0 allows remote attackers to create MCP sessions via POST /mcp. The HTTP transport calls createMcpExpressApp without an authProvider, and its initialize branch creates and connects a session without middleware authorization. Any client with network access to self-hosted HTTP mode can enumerate and invoke tools, including server-key-backed deepseek_chat operations.

CVSS severity5.3
Medium
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authentication in DeepSeek MCP Server 1.4.2 through 1.7.0 allows remote attackers to create MCP sessions via POST /mcp. The HTTP transport calls createMcpExpressApp without an authProvider, and its initialize branch creates and connects a session without middleware authorization. Any client with network access to self-hosted HTTP mode can enumerate and invoke tools, including server-key-backed deepseek_chat operations.

The record

CVE
CVE-2026-55605
Published
Jul 9, 2026
Updated
Jul 9, 2026
Vendor
arikusi
Product
DeepSeek MCP Server
Classifications
CWE-306, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 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=>= 1.4.2, < 1.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

arikusi · DeepSeek MCP Serverversion=>= 1.4.2, < 1.8.0

Published CVSS scores

5.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 exploitPublished

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1190Exploit Public-Facing Application

Public exploit references

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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