Egress Allowlist
A security control restricting the network destinations an AI agent (or its tool sandbox) can reach to a predefined list of approved domains, APIs, or endpoints. Egress allowlisting is one of the highest-ROI defenses against Indirect Prompt Injection (XPIA) and Data Poisoning: it doesn't matter if a payload successfully hijacks the model if the exfiltration destination is blocked at the network layer. Several 2025 high-CVSS injection incidents (notably CamoLeak) worked partially because a whitelisted proxy or internal domain served as an exfiltration path—so allowlists have to be narrow, not broad.
Written by Max Zeshut
Founder at Agentmelt · Last updated Sep 9, 2026
Frequently asked questions
- What should be on the allowlist?
- Only the specific APIs and domains the agent's tools genuinely need: your own API endpoints, the LLM provider(s), vetted third-party services the agent integrates with, and nothing else. Beware of allowlisting entire cloud storage domains (`*.s3.amazonaws.com`) or image proxies—these become exfiltration surfaces. If a tool needs to call an external domain, add that specific domain, not the parent.
- How do you handle agents that browse the open web?
- For agents that must browse the general web (research agents, competitive intelligence), the allowlist logic inverts: allow web browsing but block *tool actions* that transact, send data externally, or mutate state until the agent returns to a sandboxed context. Separate 'read the world' from 'act on the world' at the architecture layer.