CVE-2026-58057
Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity
Description
Flowise before 3.1.3 validates Custom MCP stdio environment variables against a denylist using a case-sensitive comparison, so on Windows, where environment names are case-insensitive, supplying 'node_options' bypasses the NODE_OPTIONS denylist entry. An authenticated user who can configure a Custom MCP node can thereby inject NODE_OPTIONS --require and execute arbitrary code in the Flowise server context.
INFO
Published Date :
June 28, 2026, 2:16 a.m.
Last Modified :
July 6, 2026, 2:54 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | LOW | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | LOW | [email protected] |
Solution
- Update Flowise to version 3.1.3 or later.
- Review and restrict access to Custom MCP node configuration.
- Monitor server logs for suspicious activity.
Public PoC/Exploit Available at Github
CVE-2026-58057 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-58057.
| URL | Resource |
|---|---|
| https://github.com/FlowiseAI/Flowise/pull/6471 | Issue Tracking Patch |
| https://github.com/bikini/exploitarium/tree/main/flowise-mcp-env-case-bypass-poc | Exploit Third Party Advisory |
| https://www.vulncheck.com/advisories/flowise-custom-mcp-environment-variable-denylist-bypass-via-case-sensitivity | Exploit Patch Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-58057 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-58057
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
The Project shares all information on MCP related CVE's published
mcp mcp-security mcp-cve
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-58057 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-58057 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 06, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:flowiseai:flowise:*:*:*:*:*:*:*:* versions up to (excluding) 3.1.3 Added Reference Type VulnCheck: https://github.com/bikini/exploitarium/tree/main/flowise-mcp-env-case-bypass-poc Types: Exploit, Third Party Advisory Added Reference Type VulnCheck: https://github.com/FlowiseAI/Flowise/pull/6471 Types: Issue Tracking, Patch Added Reference Type VulnCheck: https://www.vulncheck.com/advisories/flowise-custom-mcp-environment-variable-denylist-bypass-via-case-sensitivity Types: Exploit, Patch, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 29, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-58057', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-29T12:23:43.023783Z'} -
New CVE Received by [email protected]
Jun. 28, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Flowise', 'product': 'Flowise', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.1.3', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '3.1.3', 'versionType': 'semver'}], 'packageURL': 'pkg:npm/flowise', 'defaultStatus': 'unaffected'}] Added Description Flowise before 3.1.3 validates Custom MCP stdio environment variables against a denylist using a case-sensitive comparison, so on Windows, where environment names are case-insensitive, supplying 'node_options' bypasses the NODE_OPTIONS denylist entry. An authenticated user who can configure a Custom MCP node can thereby inject NODE_OPTIONS --require and execute arbitrary code in the Flowise server context. Added CVSS V4.0 AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L Added CWE CWE-178 Added Reference https://github.com/bikini/exploitarium/tree/main/flowise-mcp-env-case-bypass-poc Added Reference https://github.com/FlowiseAI/Flowise/pull/6471 Added Reference https://www.vulncheck.com/advisories/flowise-custom-mcp-environment-variable-denylist-bypass-via-case-sensitivity