CISA flags data-theft bug in NSA-built OT networking tool

The Cybersecurity and Infrastructure Security Agency (CISA) is warning anyone who uses GrassMarlin, a tool developed by the National Security Agency (NSA), about a new vulnerability that attackers can use to snoop on sensitive information.

First reported by Grady DeRosa, senior industrial pentester at Dragos, the weak spot affects all versions of GrassMarlin, a tool developed and open-sourced by the NSA to support network security at critical infrastructure organizations, industrial control systems, and SCADA networks.

GrassMarlin went EOL in 2017, so there are no fixes in the works. CISA just recommends to ensure control systems and devices are not accessible via the open internet, firewalled networks and devices are isolated from business networks, and remote access is established securely.

CISA did not - in typical fashion - offer too many details regarding CVE-2026-6807 (5.5), but confirmed that successful exploits could lead to sensitive information being disclosed.

However, in an advisory published ...