# CVE-2026-56274: Flowise OS command injection in Custom MCP Server feature

Source: https://junglewise.ai/threats/cve-2026-56274-flowise-os-command-injection-in-custom-mcp-server-feature  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-23. Updated: 2026-06-23  
License: CC BY 4.0 with a link back

CVE-2026-56274 · Severity: critical · CVSS 9.9 · Published 2026-06-23

Flowise, an open-source tool for building LLM applications, contains security flaws in its Model Context Protocol (MCP) feature. These flaws allow any user with an account or API access to bypass security filters and run unauthorized commands on the underlying server. An attacker could use this to steal sensitive data, disrupt operations, or gain full control over the host system.

Technologies: [flowise (npm)](https://junglewise.ai/threats/technologies/flowise), [flowise-components (npm)](https://junglewise.ai/threats/technologies/flowise-components). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-56274 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-56274 being exploited in the wild.

**How severe is CVE-2026-56274?** Critical severity, with a CVSS score of 9.9, published 23 June 2026.

**Which products and versions are affected?** flowise (npm) SEMVER:introduced=0,fixed=3.1.2; flowise-components (npm) SEMVER:introduced=0,fixed=3.1.2.

**Is there a fix for CVE-2026-56274?** Yes. flowise (npm): upgrade to 3.1.2 or later; flowise-components (npm): upgrade to 3.1.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-56274 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-56274?** Check whether you run flowise (npm) or flowise-components (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- flowise (npm): upgrade to 3.1.2 or later

  ```sh
  npm install flowise@3.1.2
  ```

- flowise-components (npm): upgrade to 3.1.2 or later

  ```sh
  npm install flowise-components@3.1.2
  ```


## Technical details

Flowise versions prior to 3.1.2 are vulnerable to Remote Code Execution (RCE) via three distinct bypasses in the Custom MCP Server feature. First, the 'validateCommandFlags' blocklist fails to include dangerous subcommands like 'docker build', which can be used to execute arbitrary instructions from a remote Dockerfile. Second, the blocklist for 'npx' only filters the short '-y' flag but misses the '--yes' alias, allowing the execution of malicious npm packages. Third, a regex flaw in 'validateArgsForLocalFileAccess' (using '/^\/[^/]/') can be bypassed by using double slashes (e.g., '//etc/passwd'), allowing attackers to execute local scripts. These vulnerabilities require low-privileged authenticated access or API permissions to modify chatflows. The issues are addressed in version 3.1.2.

## Affected products

- FlowiseAI Flowise < 3.1.2
- FlowiseAI flowise-components < 3.1.2

## Identifiers

- CVE-2026-56274
- GHSA-m99r-2hxc-cp3q

## Timeline

- 2026-05-14: advisory: Vendor security advisory published on GitHub
- 2026-06-23: disclosed: CVE published and NVD record created

## References

- [https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-m99r-2hxc-cp3q](https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-m99r-2hxc-cp3q)
- [https://www.vulncheck.com/advisories/flowise-remote-code-execution-via-mcp-security-bypass-in-validatecommandflags-and-validateargsforlocalfileaccess](https://www.vulncheck.com/advisories/flowise-remote-code-execution-via-mcp-security-bypass-in-validatecommandflags-and-validateargsforlocalfileaccess)

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