Flowise - RCE (CVE-2025-59528)

CVE-2025-59528 is a critical remote code execution vulnerability in Flowise version 3.0.5, stemming from unsafe handling of user input in the CustomMCP node. Attackers can exploit this flaw by supplying malicious JavaScript code, which is executed with full Node.js privileges, potentially granting access to sensitive system resources and enabling arbitrary command execution. This vulnerability poses a severe risk, as it allows unauthenticated attackers to fully compromise affected systems. The issue has been addressed in Flowise version 3.0.6.

CrowdSec has been tracking this vulnerability and its exploits since 17th of June 2026.

Based on data from the CrowdSec network, nearly all observed exploitation of CVE-2025-59528 is fully opportunistic, with attackers indiscriminately scanning the entire internet. These attacks are automated and lack any form of target selection or reconnaissance. CrowdSec network telemetry also shows that exploitation of CVE-2025-59528 has significantly declined over the past week. Attack volumes are well below the long-term average, suggesting attackers are rapidly losing interest. The vulnerability appears to be falling out of active use across most threat landscapes.

Attackers exploit the Flowise API endpoint /api/v1/node-load-method/customMCP by sending malicious JSON payloads to the mcpServerConfig input, enabling remote code execution with Node.js privileges. Initial access is typically gained via authentication to /api/v1/auth/login, after which crafted requests are used to trigger the vulnerability.