CVE-2026-28792: TinaCMS CLI Dev Server Vulnerable to Cross-Origin File Exfiltration via CORS Misconfiguration + Path Traversal in TinaCMS

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.7%, percentile 51: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 51% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.
• Only applies if your dependency tree includes @tinacms/cli (npm) < 2.1.8, fixed in 2.1.8. Check your lockfile, including transitive dependencies.

What it is

Tina is a headless content management system. Prior to 2.1.8 , the TinaCMS CLI dev server combines a permissive CORS configuration (Access-Control-Allow-Origin: ) with the path traversal vulnerability (previously reported) to enable a browser-based drive-by attack. A remote attacker can enumerate the filesystem, write arbitrary files, and delete arbitrary files on developer's machines by simply tricking them into visiting a malicious website while tinacms dev is running. This vulnerability is fixed in 2.1.8.

From the GitHub advisory

Summary The TinaCMS CLI dev server combines a permissive CORS configuration (Access-Control-Allow-Origin: ) with the path traversal vulnerability (previously reported) to enable a browser-based drive-by attack. A remote attacker can enumerate the filesystem, write arbitrary files, and delete arbitrary files on developer's machines by simply tricking them into visiting a malicious website while tinacms dev is running.

Details The TinaCMS dev server sets permissive CORS headers that allow any origin to make cross-origin requests:

- packages/@tinacms/cli/src/server/server.ts:

- packages/@tinacms/cli/src/next/vite/plugins.ts:

When combined with the path traversal vulnerability, this creates a complete attack chain. Attack Scenario

Weakness type: CWE-22, CWE-942.

Product: @tinacms/cli (npm) · Assigned by: GitHub_M · Published: 2026-03-12

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: required (a user must click/open something)
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.65% probability of exploitation activity in the next 30 days; percentile 51.

Timeline

• 2026-03-12 — CVE record published by GitHub_M
• 2026-03-12 — GitHub-reviewed advisory GHSA-8pw3-9m7f-q734 published (critical)
• 2026-03-13 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-8pw3-9m7f-q734 github.com
2. CVE.org record CVE-2026-28792 cve.org
3. NVD entry CVE-2026-28792 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

Critical npm advisories · Today’s Security Digest