A high-severity security flaw in Langflow, an open-source platform for building AI applications, is currently being actively exploited. Identified as CVE-2026-5027, this vulnerability allows attackers to write files to arbitrary locations on the server’s filesystem, potentially leading to remote code execution.
Langflow is widely used by AI development teams for its visual interface that simplifies the creation of AI agents and workflows. The platform has garnered significant attention, with over 149,000 stars and 9,200 forks on GitHub. However, this popularity also makes it an attractive target for cyber threats.
The vulnerability resides in the ‘POST /api/v2/files’ endpoint, which fails to properly sanitize the ‘filename’ parameter in multipart form data. This oversight enables attackers to exploit path traversal sequences (‘../’) to write files outside the intended directory structure. The flaw was initially discovered by Tenable, a cybersecurity firm, which disclosed the issue in late March 2026 after multiple attempts to contact the project’s maintainers.
Despite the disclosure, the vulnerability remains unpatched, leaving systems running Langflow exposed to potential attacks. The Common Vulnerability Scoring System (CVSS) has rated this flaw with a score of 8.8, categorizing it as high severity. The associated Common Weakness Enumeration (CWE) identifier is CWE-22, which pertains to improper limitation of a pathname to a restricted directory, commonly known as a path traversal vulnerability.
In response to the ongoing exploitation, security experts recommend that organizations using Langflow implement immediate mitigations. These include sanitizing the ‘filename’ parameter to prevent arbitrary file writes, validating file paths before writing to the filesystem, and enforcing strict access controls for file operations. Additionally, monitoring systems for unusual activity and reviewing server logs can help detect potential exploitation attempts.
The active exploitation of CVE-2026-5027 underscores the critical importance of timely vulnerability management in open-source projects. Organizations relying on Langflow should prioritize implementing the recommended mitigations to safeguard their systems against potential attacks. This incident also highlights the need for open-source communities to establish robust communication channels and response strategies to address security vulnerabilities promptly.
