Summary
The TinaCMS CLI dev server configures Vite with server.fs.strict: false, which disables Vite's built-in filesystem access restriction. This allows any unauthenticated attacker who can reach the dev server to read arbitrary files on the host system
Details
When running tinacms dev, the CLI starts a Vite dev server configured in:
packages/@tinacms/cli/src/next/vite/index.ts
server: {
host: configManager.config?.build?.host ?? false,
...
fs: {
strict: false, // Disables Vite's filesystem access restriction
},
},
TinaCMS middleware only intercepts specific route prefixes (/media/*, /graphql, /altair, /searchIndex). Any request to a path outside these routes falls through to Vite's default static file handler, which will serve the file directly from the absolute path on the filesystem.
Additionally, the server enables permissive CORS (cors() with no origin restriction), which may further facilitate browser-based exploitation such as DNS rebinding attacks.
PoC
Prerequisites: TinaCMS CLI dev server running (default port 4001).
- Read system files directly:
curl http://localhost:4001/etc/passwd
curl http://localhost:4001/etc/hostname
Vite resolves and serves the absolute path directly from the filesystem.
Impact
Any developer running tinacms dev in an environment where the dev server port is reachable by an attacker. This includes:
-
Cloud IDEs (GitHub Codespaces, Gitpod) where ports are automatically forwarded and publicly accessible
-
Docker or VM setups with port forwarding configured
-
Misconfigured environments binding to 0.0.0.0 via the build.host config option
-
Systems targeted via DNS rebinding attacks, leveraging the unrestricted CORS policy
-
Local environments with malicious dependencies running on the same machine
An attacker who can reach port 4001 can:
-
Read any file readable by the server process (/etc/passwd, /etc/shadow, SSH private keys)
-
Exfiltrate environment variables and secrets via /proc/self/environ
-
Access cloud credentials and API keys from configuration files
References
alaeddine03 Reporter
Summary
The TinaCMS CLI dev server configures Vite with
server.fs.strict: false, which disables Vite's built-in filesystem access restriction. This allows any unauthenticated attacker who can reach the dev server to read arbitrary files on the host systemDetails
When running
tinacms dev, the CLI starts a Vite dev server configured in:packages/@tinacms/cli/src/next/vite/index.tsTinaCMS middleware only intercepts specific route prefixes (/media/*, /graphql, /altair, /searchIndex). Any request to a path outside these routes falls through to Vite's default static file handler, which will serve the file directly from the absolute path on the filesystem.
Additionally, the server enables permissive CORS (cors() with no origin restriction), which may further facilitate browser-based exploitation such as DNS rebinding attacks.
PoC
Prerequisites: TinaCMS CLI dev server running (default port 4001).
Vite resolves and serves the absolute path directly from the filesystem.Impact
Any developer running tinacms dev in an environment where the dev server port is reachable by an attacker. This includes:
Cloud IDEs (GitHub Codespaces, Gitpod) where ports are automatically forwarded and publicly accessible
Docker or VM setups with port forwarding configured
Misconfigured environments binding to 0.0.0.0 via the build.host config option
Systems targeted via DNS rebinding attacks, leveraging the unrestricted CORS policy
Local environments with malicious dependencies running on the same machine
An attacker who can reach port 4001 can:
Read any file readable by the server process (/etc/passwd, /etc/shadow, SSH private keys)
Exfiltrate environment variables and secrets via /proc/self/environ
Access cloud credentials and API keys from configuration files
References