From 2fe4e06cc23bda9d8a719fbcf3d3712e42d450de Mon Sep 17 00:00:00 2001 From: viyatb-oai Date: Tue, 18 Aug 2026 21:11:17 +0000 Subject: [PATCH] Document secure devcontainer DNS exfiltration risk (#39283) ## Why The secure devcontainer's firewall does not apply its domain allowlist to DNS traffic, so it does not provide secure DNS resolution for untrusted code. ## What changed Document the DNS exfiltration risk, limit the devcontainer recommendation to trusted repositories, and describe filtering DNS through a restricted resolver as a partial mitigation. Clarify that allowlisted HTTPS destinations remain a possible exfiltration path. GitOrigin-RevId: 73cc7d29f8de17013c01411f8c20b8b5e1199b24 --- .devcontainer/README.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/.devcontainer/README.md b/.devcontainer/README.md index 3b07f2b440..74da60f601 100644 --- a/.devcontainer/README.md +++ b/.devcontainer/README.md @@ -22,6 +22,8 @@ Use `devcontainer.secure.json` when you want a stricter runtime profile for runn This profile keeps the stricter networking isolated to the customer path instead of changing the default Codex contributor container. +The firewall does not apply its domain allowlist to DNS traffic, so code from an untrusted repository can exfiltrate data through DNS. This devcontainer does not provide secure DNS resolution. Use it only with trusted repositories. To mitigate DNS exfiltration, implement your own DNS filtering and restrict outbound DNS traffic to the filtered resolver; this does not make untrusted repositories safe because they can still exfiltrate data through allowed HTTPS destinations. + Start it from the CLI with: ```bash