Executive brief
docker-socket-proxy is a security proxy that restricts access to the Docker daemon API. When the CONTAINERS environment variable is enabled, the proxy fails to properly restrict read-only endpoints, allowing attackers to download entire container filesystems, read arbitrary files, and inspect container processes and logs without authorization. This bypasses the intended security controls and could expose sensitive data, credentials, and application code stored in containers.
Technical details
The vulnerability is an authorization bypass in the /containers Docker API namespace. When CONTAINERS=1 is set, the proxy should restrict dangerous operations, but four GET endpoints are not properly gated: /containers/{id}/archive (read files), /containers/{id}/export (download full filesystem as tar), /containers/{id}/logs (read container output), and /containers/{id}/top (list processes). These are read-only operations that do not require POST access, allowing any client with network access to the proxy to extract sensitive data from all containers. The root cause is incomplete endpoint filtering in the HAProxy configuration. No patch version is mentioned; exploitation requires network access to the exposed proxy port and knowledge of container IDs (which can be enumerated via /containers/json).
Affected products
- Tecnativa docker-socket-proxy
Timeline
- 2026-08-22: disclosed: CVE-2026-78122 published
- 2026-08-15: other: Proof of concept posted to GitHub Gist