CVE-2026-29066 — @tinacms/cli
MEDIUMCVE-2026-29066 is a medium-severity (CVSS 6.2) Information Exposure vulnerability in @tinacms/cli. A fix is available for @tinacms/cli — see the affected versions and patch details below.
Arbitrary File Read via Disabled Vite Filesystem Restriction in TinaCMS CLI
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-29066.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-29066 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@tinacms/clinpmDescription
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
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @tinacms/cli | all versions | 2.1.8npm install @tinacms/cli@2.1.8 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @tinacms/cli, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @tinacms/cli to 2.1.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-29066 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-29066 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-29066. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
How to detect CVE-2026-29066
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2026-29066 -u https://target- Template
- TinaCMS - Path Traversal
- Severity
- medium
- Impact
- Unauthenticated attackers can read arbitrary files on the host system, potentially exposing sensitive information.
- Remediation
- Update to version 2.1.8 or later.
Template by ProjectDiscovery nuclei-templates (theamanrawat), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2026-29066 in your dependencies?
O3 Security finds CVE-2026-29066 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.