CVE-2025-26319

CVE-2025-26319 is an arbitrary file upload flaw (CWE-434) in the /api/v1/attachments API endpoint of FlowiseAI Flowise v2.2.6, a self-hosted open-source platform for building AI agent and LLM workflows. The endpoint accepts uploads without proper validation, and because the flaw is network-reachable with no authentication and no user interaction required (per the CVSS vector), a remote unauthenticated attacker can trigger it by sending crafted upload requests. The critical 9.8 score with high ratings for confidentiality, integrity, and availability indicates that successful abuse can lead to full compromise of the host, plausibly including remote code execution via uploaded files. Anyone running Flowise v2.2.6 is affected, and the risk is highest for instances exposed to the internet. Exploitation appears to be ongoing: a public proof-of-concept is available on GitHub, EPSS puts the 30-day exploitation probability at 55.9% (99th percentile), and security news reports attackers actively exploiting a critical Flowise flaw against the product's roughly 12,000+ internet-exposed instances.

What to do: Upgrade Flowise to the latest release beyond v2.2.6 (no specific fixed version is stated in the available data, so verify the fix with the vendor's changelog), and keep internet exposure of /api/v1/attachments restricted — place Flowise behind a reverse proxy with authentication or limit it to trusted networks. Review servers for unexpected or recently created uploaded files and check access logs for unauthenticated POSTs to /api/v1/attachments as evidence of exploitation.