CVE-2026-82456: argocd-mcp 0.8.0 Authentication Bypass via Unauthenticated HTTP

Severity: critical (CVSS 10.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-08-29 · updated 2026-09-23
Weakness: CWE-1327

Description

argocd-mcp 0.8.0 binds its HTTP transport to every network interface and accepts MCP sessions without requiring caller credentials when ARGOCD_API_TOKEN is configured. Attackers who can reach the listener can invoke the full tool surface using the operator's stored token to create applications, request syncs, and modify Argo CD resources.

Affected products

argoproj-labs argocd-mcp: from 0.8.0 before 0.9.0 — fixed in 0.9.0

How to fix

Upgrade to a fixed version: argoproj-labs argocd-mcp 0.9.0. Check the vendor advisory for mitigations.

References

https://github.com/argoproj-labs/mcp-for-argocd
https://github.com/argoproj-labs/mcp-for-argocd/security/advisories/GHSA-rp45-5x3v-48mr
https://www.vulncheck.com/advisories/argocd-mcp-0.8.0-authentication-bypass-via-unauthenticated-http
https://github.com/argoproj-labs/mcp-for-argocd/security/advisories/GHSA-rp45-5x3v-48mr

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