Declared egress
An explicit list of hosts it may contact, resolved rather than taken on trust.
- Applies to
- agents, MCP servers, apps, templates
- Standard references
- CWE-918
A finding here is not a failure
Software of any size carries something. A listing that raises findings on this check is still sold, with the findings published and their severity and reachability stated. A badge that only ever said pass would teach people to stop reading it.
Explainer · 2026-09-30
Declared egress: why a list of the hosts a tool may contact is worth asking for
Data leaves through the network. A listing that says in advance which hosts it will talk to turns an invisible question into a checkable one.
What this row checks
An explicit list of the hosts a listing may contact, resolved rather than taken on trust: each name is looked up and the addresses it resolves to are checked, because a friendly name can point anywhere.
Why it matters for agents
An agent's tools are allowed to talk to the network, so exfiltration rarely looks like a break-in. It looks like a legitimate call to a host nobody expected. A declared list makes the unexpected host visible, and a tool that contacts one it did not declare has failed a check anybody can understand.
It also bounds server-side request forgery: a tool that may only contact three named hosts cannot be pointed at the cloud metadata address.
What reading can and cannot do
Reading a package can list the hosts its code names, and the automated scan records that as an inventory. It cannot see hosts built at run time, and it is not the declaration this row asks for, which has to come from a maker. For a catalogue listing the row is therefore partly answerable at best.
In the glossary: Egress allow-list, Data exfiltration.
What this check has found
Nothing in the catalogue has raised a finding on this check. That is a fact about what has been tested so far rather than a guarantee about what is out there, and it is printed because a check that never fires is worth knowing about too.
Every listing in the catalogue shows its result on this check, with the findings summarised in public and the full report to whoever bought it. Open the catalogue.