CVE-2026-55454

The Caddy administrative API (by default without authentication) listens on address 0.0.0.0:2019 inside the Docker container. Although this port is not directly published to the host by docker-compose.yml, it is accessible from the Appsmith server process. An attacker with low privileges can use the SSRF vulnerability to send a POST request to the /load endpoint (or any other admin API call) to address http://0.0.0.0:2019/, allowing complete replacement of the active Caddy configuration.

An attacker can completely replace the configuration of the running Caddy reverse proxy, leading to takeover of control over application network traffic, potential data disclosure (C:H), modification or destruction of resources (I:H), and disruption of service availability (A:H) — with effects extending beyond container boundaries (Scope: Changed).

Appsmith should be updated to version 2.1 or later, where the vulnerability has been fixed. Until the update, it is recommended to restrict network access to port 2019 inside the container and verify the docker-compose configuration for network isolation.

Appsmith in versions prior to 2.1, running in a containerized environment (Docker).