Hottest cybersecurity open-source tools of the month: June 2026 Presented here is a curated selection of noteworthy open-source cybersecurity solutions that have drawn recognition for their ability to enhance security postures across diverse settings. OWASP Agent Memory Guard: Stop AI agents from being weaponized through their own memory AI agents keep memory across sessions. Conversation history, vector stores, scratchpads, and RAG indexes persist between runs, and anything written into that store becomes a privileged input the agent reads back later. An attacker who plants text in the wrong field can override an agent’s instructions, pull out user data, or steer future tool calls, and the effect survives across sessions because the memory does. Agent Memory Guard is an open-source runtime defense layer that sits between an agent and its memory store, screening every read and write through a pipeline of detectors and a YAML policy. Agent Threat Rules: Open detection rule format for AI agent security threats AI agents run inside coding assistants, MCP servers, and multi-agent frameworks, and the access that makes them useful also opens paths to prompt injection, tool poisoning, and credential theft. Public CVE feeds carry agent-execution flaws that reach production faster than the tooling built to catch them. Agent Threat Rules, or ATR, is an open detection format aimed at this category of attack. AgentGG: Open-source agentic SAST scanner Static analysis tools have spent years matching source code against known-bad patterns and handing engineers long lists of candidate issues to triage by hand. AgentGG approaches the same job with AI agents that read the code, follow imports, walk the call graph, and confirm a finding before they report it. The project is an open-source agentic SAST scanner released under the Apache 2.0 license. DockSec: Open-source AI-powered Docker security scanner DockSec is an OWASP Incubator Project