A high-severity security vulnerability has been identified in Langflow, an open-source low-code platform designed for building artificial intelligence (AI) applications, and is now being actively exploited in the wild, according to VulnCheck.
The flaw, tracked as CVE-2026-5027 (CVSS score: 8.8), is a path traversal issue that could enable an attacker to write files to any location on the filesystem.
"The 'POST /api/v2/files' endpoint fails to sanitize the 'filename' parameter from the multipart form data, allowing an attacker to write files to arbitrary locations on the filesystem through path traversal sequences ('../')," stated Tenable, the firm that discovered the vulnerability, in an alert issued in late March 2026.
The cybersecurity firm noted it made three attempts to contact the project maintainers in January and February 2026, prior to disclosing the issue details on March 27.
Caitlin Condon, vice president of security research at VulnCheck, stated in a LinkedIn post that the vulnerability facilitates remote code execution.
"Since Langflow enables unauthenticated auto-login by default, no credentials are required to access the vulnerable endpoint, and a single unauthenticated request is enough to obtain a valid session token before proceeding with exploitation," Condon added.
So far, exploitation attempts appear to leverage the bug to write test files on compromised systems. Data from Censys indicates approximately 7,000 Langflow instances are publicly exposed on the internet, with the majority located in North America.
This attack effort follows a wave of exploitation activity targeting other Langflow vulnerabilities this year, including CVE-2026-0770, CVE-2026-33017, CVE-2026-21445, and CVE-2025-34291, the last of which has been used by the Iranian state-sponsored group MuddyWater.
"This activity highlights a growing trend of attackers targeting the infrastructure and tools organizations use to build and deploy AI applications," the company said in a statement provided to The Hacker News.
Update
When asked for comment on the patch status, Tenable informed The Hacker News via email that the maintainer of the langflow-base package confirmed the vulnerability was fixed in Langflow version 1.9.0, released on April 15, 2026. Users are advised to update to the latest version for optimal protection.
(The story was updated after publication to include details about the patch availability.)