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Cvefeed High Severity Advisories Jun 23, 2026 CVE-2026-56274 - Flowise - Remote Code Execution via MCP Security Bypass in validateCommandFlags and validateArgsForLocalFileAccess cvefeed.io Open source

cvefeed.io • June 23, 2026

Flowise before 3.1.2 contains multiple OS command injection vulnerabilities in the Custom MCP Server feature due to incomplete command-flag validation and a regex bypass in local file access restrictions. An attacker with a Flowise account of any role, or API access with view/update permissions for chatflows, can configure a malicious MCP server to bypass the validateCommandFlags blocklist (for example, 'docker build' is not blocked, and 'npx --yes' is not blocked while only '-y' is) and the validateArgsForLocalFileAccess checks, resulting in execution of arbitrary commands on the Flowise host.

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The full story

This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Critical Remote Code Execution Flaw Discovered in Flowise MCP Server Flowise has disclosed a critical remote code execution vulnerability, tracked as CVE-2026-56274, affecting versions prior to 3.1.2 of its Custom MCP Server feature. The flaw allows attackers to exploit multiple OS command injection paths in the validateCommandFlags and validateArgsForLocalFileAccess functions. Attackers with any Flowise account role or API access can configure a malicious MCP server, leading to arbitrary command execution on the Flowise host. The vulnerability has a CVSS score of 9.9, indicating high severity and remote exploitability. Organizations are advised to upgrade to Flowise version 3.1.2 or later and review their MCP server configurations. Three bypass techniques have been identified, including an incomplete Docker argument blocklist and a regex bypass in local file access checks. The vulnerability was published on June 23, 2026, and poses a significant risk to affected systems. 2 sources 78

Extracted Entities

Cvefeed High Severity Advisories Jun 23, 2026 CVE-2026-56274 - Flowise - Remote Code Execution via MCP Security Bypass in validateCommandFlags and validateArgsForLocalFileAccess cvefeed.io Open source

The full story

Extracted Entities

Attack Types (1)

CVEs (1)

CWE Weaknesses (1)

Domains (1)

MITRE ATT&CK (1)