Summary
TinaCMS CLI has Arbitrary File Read via Disabled Vite Filesystem Restriction
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
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
CVE-2026-29066 has a CVSS score of 6.2 (Medium). The vector is requires local access, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.1.8); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-29066? CVE-2026-29066 is a medium-severity security vulnerability in @tinacms/cli (npm), affecting versions < 2.1.8. It is fixed in 2.1.8.
- How severe is CVE-2026-29066? CVE-2026-29066 has a CVSS score of 6.2 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of @tinacms/cli are affected by CVE-2026-29066? @tinacms/cli (npm) versions < 2.1.8 is affected.
- Is there a fix for CVE-2026-29066? Yes. CVE-2026-29066 is fixed in 2.1.8. Upgrade to this version or later.
- Is CVE-2026-29066 exploitable, and should I be worried? Whether CVE-2026-29066 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-29066 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-29066? Upgrade
@tinacms/clito 2.1.8 or later.