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Cato AI Labs found that injected instructions arriving via MCP servers or web results could make Cursor's agent widen its own sandbox write permissions or exploit a symlink-check fallback, then run commands outside the sandbox as the user. Both flaws are rated CVSS 9.8 and were fixed in Cursor 3.0 on 2026-04-02 after Cursor initially rejected the reports.
Check Point Research found that Cursor bound MCP approval to a configuration's name rather than its contents, so a collaborator with repository write access could swap an approved harmless command for a malicious one that ran on each project open. Cursor 1.3, released 2025-07-29, prompts for approval on any MCP configuration change.
Cursor's advisory states that the agent could create new workspace dotfiles without approval, so injected instructions arriving via an external MCP source could write an MCP configuration that launched attacker commands. Aim Security researchers reported it; it is rated CVSS 8.5 and fixed in Cursor 1.3.9.