CVE-2026-82456Public exploitNetwork attack vectorHinoki check available

Unauthenticated resource control via exposed HTTP listener

Published Aug 29, 2026 · Updated Aug 29, 2026

Authentication bypass in Argo CD MCP Server 0.8.0 allows remote attackers to modify Argo CD resources through its HTTP listener. The HTTP transport calls app.listen(port) without a host, accepts sessions without inbound credentials, and reuses ARGOCD_API_TOKEN for outbound Argo CD requests. Network reachability and a configured token are required; write-capable tokens permit application creation, synchronization, deletion, and resource actions without user interaction.

CVSS severity10.0
Critical
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Authentication bypass in Argo CD MCP Server 0.8.0 allows remote attackers to modify Argo CD resources through its HTTP listener. The HTTP transport calls app.listen(port) without a host, accepts sessions without inbound credentials, and reuses ARGOCD_API_TOKEN for outbound Argo CD requests. Network reachability and a configured token are required; write-capable tokens permit application creation, synchronization, deletion, and resource actions without user interaction.

The record

CVE
CVE-2026-82456
Published
Aug 29, 2026
Updated
Aug 29, 2026
Vendor
Argo Project
Product
Argo CD MCP Server
Classifications
CWE-306, CWE-346, CWE-1327, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 29, 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=0.8.0 <0.9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Argo Project · Argo CD MCP Serverversion=0.8.0 <0.9.0

Published CVSS scores

10.0National Vulnerability DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
10.0Argo ProjectCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

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
CWE-346Origin Validation Error
CWE-1327Binding to an Unrestricted IP Address
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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