praktor is a multi-agent Claude Code orchestrator with Telegram input and output, Docker isolation, and a Mission Control UI. Prior to 0.9.1, both Telegram upload sites in "internal/telegram/bot.go" concatenate the attacker-controlled document filename into a destination path without sanitization, and "path.Join" collapses parent-directory traversal. A remote Telegram user who can message the bot can therefore write outside "uploads/" within the persistent agent workspace mounted at "/workspace/agent". Because "allow_from: []" permits all senders by default, no prior authentication or privilege is required in that configuration. The attacker can plant or overwrite "CLAUDE.md", instruction, skill, hook, or configuration files that the Claude agent reads and operates on across later runs, turning a document upload into stored instruction injection. The demonstrated arbitrary-write scope is the persistent agent workspace volume, not an unrestricted host-filesystem write. This issue is fixed in version 0.9.1.