Fake Bug Report Hijacks AI Coding Agents at Scale

Tenet Security demonstrated at DEF CON 34 an "agentjacking" attack where an attacker POSTs a crafted error event containing markdown-formatted malicious instructions to a publicly exposed Sentry DSN ingest endpoint; when a developer asks an MCP-connected coding agent (Cursor, Claude Code) to debug, the agent retrieves the injected event, treats it as authoritative remediation, and executes commands that pull a malicious npm package and exfiltrate AWS, GitHub, npm, Kubernetes and CI/CD credentials. Controlled testing across 100+ organizations succeeded 85 percent of the time; no CVE was assigned, and Sentry deployed only a payload-string filter. Tenet also released agent-jackstop, drop-in hardening configs (egress allowlist, command approval, credential-read blocking) for Cursor and Claude Code.