CVE-2026-5027: Langflow Path Traversal — Unauthenticated File Write Risk (June 2026)

CVE-2026-5027 — Langflow Path Traversal

CVE-2026-5027 is a high-severity vulnerability in the Langflow AI development platform, currently under active exploitation. The flaw allows unauthenticated attackers to write arbitrary files to exposed servers due to a path traversal bug combined with default auto-login, creating a critical risk for any publicly accessible instance.

Attack Vector

Attackers exploit CVE-2026-5027 by sending crafted requests that leverage path traversal sequences, enabling them to write files to arbitrary locations on the host system. No authentication is required, as Langflow’s default configuration enables auto-login for all users. This makes exploitation trivial for anyone with network access to the service. The vulnerability is being exploited in the wild, with attackers able to deploy web shells, backdoors, or modify application logic on vulnerable servers.

Who Is at Risk

All organizations running publicly exposed Langflow instances are at immediate risk, with approximately 7,000 such deployments identified globally. The vulnerability affects default installations with auto-login enabled, regardless of underlying operating system or cloud provider. No credentials are required for exploitation, so any internet-facing instance is vulnerable.

Patch & Mitigate

• Patch: Apply the latest Langflow security update addressing CVE-2026-5027 as soon as possible. If a patch is not yet available, restrict public access immediately.
• Workaround: Disable auto-login and restrict network access to trusted IPs or internal networks only.
• Detect: Review server logs for suspicious file write operations, unexpected new files in application directories, or anomalous HTTP requests containing path traversal patterns (e.g., '../'). Monitor for unauthorized changes to application files.

MITRE ATT&CK

• TA0005 — Defense Evasion: Attackers use file writes to bypass controls and establish persistence.
• T1105 — Ingress Tool Transfer: Arbitrary file writes enable delivery of malicious payloads to the target system.

Source: https://www.bleepingcomputer.com/news/security/path-traversal-flaw-in-ai-dev-platform-langflow-exploited-in-attacks/