Malicious files in the Downloads folder can hijack AI coding agents, researchers say
Researchers say Codex and Claude Code agents can be hijacked by files planted in the Downloads folder that contain malicious instructions, such as AGENTS.md. According to a Brandefense summary, agents should not be run in the Downloads folder, and ~/.codex/config.toml and .claude/settings.json should be checked.
Who is affected and how
- senior developer
- Start an agent only in a verified project directory, never next to files downloaded from unknown sources.
Sources
- AI coding agents fall for malicious instructions planted in the Downloads folderhelp net security · Oct 26, 2026
- Malicious File in Downloads Folder Tries to Trick AI Coding Agent Into Installing Malwarethe hacker news · Oct 26, 2026
- Malicious downloads can trick AI coding agents into compromising themselves - CSO Onlinecsoonline.com · Oct 26, 2026
- AI coding agents fall for malicious instructions planted in the Downloads folder - Help Net Securityhelpnetsecurity.com · Oct 26, 2026
- Hackers Can Hijack OpenAI Codex and Claude Code Using Malicious Files in Downloads Foldercybersecuritynews · Oct 26, 2026
- Shadowy AI Relay Disables OpenAI Codex, Claude Code Sandboxesdark reading · Oct 29, 2026
- Codex vs Claude Code vs Antigravity: $500 to $0 [2026]https://tech-insider.org/ · Oct 29, 2026
- AGENTS.md Prompt Injection via Downloads - Brandefensebrandefense.io · Oct 26, 2026
Machine-generated summary based on the titles and excerpts of the source articles. The facts come from the linked article.