The vulnerability is an arbitrary file write flaw in the POST /api/v2/files/ endpoint. Because the underlying storage layer lacks boundary containment checks, an authenticated attacker can supply a multipart file upload with a crafted filename that bypasses the HTTP-layer validation. This allows the attacker to write files to any location on the host system. Writing malicious executable scripts or reverse shells grants the attacker full control over the server, compromising confidentiality, integrity, and availability.

The affected vendor is langflow-ai and its Langflow product. Versions 1.2.0 through 1.8.1 are vulnerable. The issue was fixed in version 1.9.0, which adds proper boundary checks for file names and removes the vulnerable functionality.

The CVSS score of 10 indicates a critical flaw that could allow an attacker with authenticated API access to write files to arbitrary paths on the host. The EPSS score of 1% suggests that the probability of public exploitation is currently low, but the potential impact is severe. The vulnerability is not listed in the CISA KEV catalog, indicating that it has not yet been observed in known exploited incidents. Based on the description, it is inferred that the attacker must have an authenticated session to use the /api/v2/files/ endpoint, so the attack is likely limited to compromised user accounts or internal insiders. Once a file is written, installing executable scripts such as reverse shells would give the attacker full control over the system. The bypass of the earlier patch for CVE-2025-68478 suggests that the architectural issue in LocalStorageService is still unresolved, pointing to a design flaw that could complicate future remediation.