CVE-2025-59528: Flowise has Remote Code Execution vulnerability

Should you act?

High exploit likelihood

EPSS ranks it in the top 5% of all CVEs for likely exploitation in the next 30 days. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 86.2%, percentile 99.7: FIRST’s model estimates a 86.2% chance of exploitation activity in the next 30 days, higher than 99.7% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes flowise (npm) = 3.0.5, fixed in 3.0.6. Check your lockfile, including transitive dependencies.

What it is

Flowise is a drag & drop user interface to build a customized large language model flow. In version 3.0.5, Flowise is vulnerable to remote code execution. The CustomMCP node allows users to input configuration settings for connecting to an external MCP server. This node parses the user-provided mcpServerConfig string to build the MCP server configuration. However, during this process, it executes JavaScript code without any security validation. Specifically, inside the convertToValidJSONString function, user input is directly passed to the Function() constructor, which evaluates and executes the input as JavaScript code. Since this runs with full Node.js runtime privileges, it can access dangerous modules such as childprocess and fs. This issue has been patched in version 3.0.6.

From the GitHub advisory

Description

Cause of the Vulnerability

The CustomMCP node allows users to input configuration settings for connecting to an external MCP (Model Context Protocol) server. This node parses the user-provided mcpServerConfig string to build the MCP server configuration. However, during this process, it executes JavaScript code without any security validation.

Specifically, inside the convertToValidJSONString function, user input is directly passed to the Function() constructor, which evaluates and executes the input as JavaScript code. Since this runs with full Node.js runtime privileges, it can access dangerous modules such as childprocess and fs.

Vulnerability Flow

Weakness type: CWE-94.

Product: flowise (npm) · Assigned by: GitHub_M · Published: 2025-09-22

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 86.22% probability of exploitation activity in the next 30 days; percentile 99.7.

Timeline

• 2025-09-15 — GitHub-reviewed advisory GHSA-3gcm-f6qx-ff7p published (critical)
• 2025-09-22 — CVE record last updated
• 2025-09-22 — CVE record published by GitHub_M

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-3gcm-f6qx-ff7p github.com
2. CVE.org record CVE-2025-59528 cve.org
3. NVD entry CVE-2025-59528 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
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3. github.com github.com
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7. github.com github.com
8. github.com github.com

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