Go MCP SDK DNS Rebinding - Server-Side Request Forgery on AI Infrastructure
What's the vulnerability?
DNS Rebinding vulnerability in Go MCP SDK < 1.4.0 allows attackers to bypass 127.0.0.1/localhost protection via DNS manipulation. Attack: 1) Attacker controls DNS and resolves malicious domain to their IP, 2) Sends MCP request claiming localhost origin, 3) MCP server accepts the connection based on DNS, 4) Attacker changes DNS to point to real malicious IP, 5) Server connects to attacker-controlled endpoint thinking it's localhost. Result: SSRF, credential theft, internal network access. Affects: Go MCP SDK < 1.4.0. Fixed: v1.4.0 added DNS rebinding protection. CVSS: 8.1. Reproduction: Clone go-mcp-sdk v1.3.0, build example server, simulate DNS rebinding with /etc/hosts manipulation, observe server connecting to attacker IP.
Root Cause Analysis
Variant Analysis
Bypass and alternate trigger exploration (if present).
Verify with pruva-verify
Run the Pruva CLI to automatically fetch and execute the reproduction script.
pruva-verify REPRO-2026-00129 pruva-verify CVE-2026-34742 curl -fsSL https://pruva.dev/install.sh | sh Or Run Manually
Download the script
curl -O https://pruva.dev/api/v1/reproductions/REPRO-2026-00129/artifacts/repro/reproduction_steps.sh Make executable
chmod +x reproduction_steps.sh Run the script
./reproduction_steps.sh How Pruva Reproduced This
Watch the AI agent's step-by-step process.
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