High severity · published Aug 13, 2026
CVE-2026-73601
Flowise before 3.1.3 Remote Code Execution via Custom MCP
8.8
CVSS
1.1%
EPSS
No
On KEV
Description
Flowise versions before 3.1.3 contain a remote code execution vulnerability in the Custom MCP node when CUSTOM_MCP_PROTOCOL is set to stdio, allowing authenticated users to execute arbitrary commands by manipulating environment variables and command arguments. Attackers can abuse PYTHONWARNINGS and BROWSER environment variables with python3, or leverage the root working directory with node to bypass validation and execute system commands.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.1% · higher than 66% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FL
Flowise · FlowiseAI
before 3.1.3; before 3.1.3 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-73601
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-73601
Vendor Advisory
https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-g98q-rm45-q9h8
Third Party Advisory
https://www.vulncheck.com/advisories/flowise-before-remote-code-execution-via-custom-mcp
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