fix(markdown): bind view server to loopback - #2938
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George Ng (GeorgeNgMsft) wants to merge 1 commit into
Open
fix(markdown): bind view server to loopback#2938George Ng (GeorgeNgMsft) wants to merge 1 commit into
George Ng (GeorgeNgMsft) wants to merge 1 commit into
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Restrict the unauthenticated Markdown HTTP and WebSocket service to 127.0.0.1 and advertise the same address to collaboration clients. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 824e625d-be4c-48f5-91c7-88675b55c6e6
jebrans
approved these changes
Aug 27, 2026
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Summary
127.0.0.1https://portal.microsofticm.com/imp/v5/incidents/details/31000000567548/summary
Security context
The Markdown view service has no authentication and intentionally permits native clients that omit the
Originheader. Previously, omitting the hostname fromserver.listenbound the service to the unspecified address, making it reachable through LAN, VPN, and other network interfaces. Binding to IPv4 loopback ensures the OS accepts connections only from the local machine.Intentional access from other devices should be introduced separately as an explicit opt-in mode with authentication and transport protection rather than weakening the secure default.
Follow-up to #2935.