Analysis
New Prompt Injection Attack Vectors Through MCP Sampling
First reported · Discovered paloaltonetworks.com
Page published
Earliest dated coverage: 7 May 2026 · First observed: 17 Oct 2026 · Latest dated coverage: 7 May 2026
Coverage timeline
Single-source analysis — one report is available.
Why it matters
MCP integrations expose assistants with access to sensitive files and services to untrusted tool descriptions and shared-context manipulation, making server auditing and permission boundaries important defensive controls.
Hive Security's MCP security explainer reviews tool-description poisoning, indirect prompt injection, cross-server data exfiltration, supply-chain attacks, and excessive permissions. The article cites the malicious postmark-mcp package, reportedly found silently BCC'ing outgoing emails, as a real-world example rather than presenting a new demonstration.