CVE-2026-73601Public exploitNetwork attack vector

Authenticated command execution via Custom MCP validation bypass

Published Aug 13, 2026 · Updated Aug 13, 2026

Code injection in the Custom MCP node in Flowise before 3.1.3 allows remote authenticated users to execute commands on the server. Its stdio configuration validation permits dangerous Python environment variables and lets Node resolve proc/self/environ from the root working directory. Exploitation requires an authenticated account and CUSTOM_MCP_PROTOCOL set to stdio, and successful execution compromises the application host.

CVSS severity9.0
Critical
EPSS probability0.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in the Custom MCP node in Flowise before 3.1.3 allows remote authenticated users to execute commands on the server. Its stdio configuration validation permits dangerous Python environment variables and lets Node resolve proc/self/environ from the root working directory. Exploitation requires an authenticated account and CUSTOM_MCP_PROTOCOL set to stdio, and successful execution compromises the application host.

The record

CVE
CVE-2026-73601
Published
Aug 13, 2026
Updated
Aug 13, 2026
Vendor
FlowiseAI
Product
Flowise
Classifications
CWE-95, T1059
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 13, 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 <3.1.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

FlowiseAI · Flowiseversion=0 <3.1.3

Published CVSS scores

9.0VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA: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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-95Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
T1059Command and Scripting Interpreter

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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