Windsurf Cascade coding agent leaks developer secrets via indirect prompt injection
Windsurf (Cascade) · Aug 21, 2025 · Coding agent
What happened
Johann Rehberger disclosed that Windsurf Cascade, the coding agent inside the Windsurf editor (a VS Code fork), allowed an adversary to exfiltrate data from the developer's machine through indirect prompt injection. The vulnerabilities follow the 'lethal trifecta' pattern and were responsibly disclosed on May 30, 2025; Rehberger said receipt was acknowledged but subsequent status inquiries went unanswered, amid business disruption and the departure of Windsurf's CEO and core team.
Causal vector
Indirect prompt injection steered the coding agent into exfiltrating secrets from the developer's machine
Source
Reported by Embrace The Red (Johann Rehberger). Verified against the primary report.
Cascade's exfil path was a URL with the developer's secrets baked into it. A deterministic egress gate — allowlist of renderable and outbound domains, everything else BLOCKED — stops the leak even though the injection succeeds. Contain the action, not the prompt.
The six rule types that contain this class of failure
Per-transaction cap
Any single spend above your ceiling is BLOCKED before it moves.
Daily total
Cumulative spend across all agent calls, bounded per day.
Velocity limit
Stops runaway retry loops — the #1 cause of overnight losses.
Merchant allowlist
Only approved destinations can ever receive funds.
Category rules
Flag high-risk classes (crypto, infra, refunds) for review.
Approval threshold
Above a value, the action waits for a human.
Related incidents
Google's Antigravity IDE vulnerable to data exfiltration and remote code execution via prompt injection
Google · Nov 25, 2025
State-sponsored group automates ~80–90% of a cyber-espionage operation using Claude Code and MCP tools
Anthropic (Claude Code, abused by a threat actor) · Nov 1, 2025
Google Jules asynchronous coding agent vulnerable to multiple data exfiltration issues
Google (Jules) · Aug 13, 2025
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Every incident in this database is the result of trusting a prompt, a provider cap, or a human review cycle. sipi.bot replaces all three with one deterministic call. 67 documented failures, one control.