CVE-2026-108259

Received Received - Intake

Cross-Site Scripting in TinaCMS CLI via Branch Name Injection

Publication date: 2026-10-09

Last updated on: 2026-10-09

Assigner: GitHub, Inc.

Description

Tina is a headless content management system. Prior to 3.0.0, @tinacms/cli reads Git branch values from VERCEL_GIT_COMMIT_REF, GITHUB_BRANCH, or HEAD, incorporates the raw value into the API URL, and interpolates that URL into JavaScript string literals in packages/@tinacms/cli/src/next/codegen/index.ts and packages/@tinacms/cli/src/next/codegen/codegen/plugin.ts. A crafted Git-valid branch name containing a quote can terminate the generated string and inject an expression that executes when the generated client module is imported during a preview build. The injected code runs with the build process privileges and can read environment credentials, modify deployment artifacts, or make network requests. This issue is fixed in version 3.0.0.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-10-09

Last Modified

2026-10-09

Generated

2026-10-10

AI Q&A

2026-10-10

EPSS Evaluated

N/A

NVD

CVE-2026-108259

Affected Vendors & Products

Vendor	Product	Version / Range
tinacms	tinacms	< 3.0.0
@tinacms	cli	< 3.0.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-94	The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

Attack-Flow Graph

Executive Summary

This vulnerability affects the Tina CMS system before version 3.0.0. It involves improper handling of Git branch names that are read from environment variables like VERCEL_GIT_COMMIT_REF or GITHUB_BRANCH. A specially crafted branch name containing a quote can break out of JavaScript string literals in generated code, allowing injection of malicious expressions. These expressions execute when the client module is imported during a preview build, running with the build process privileges.

Detection Guidance

Check if your system is running Tina CMS versions prior to 3.0.0. Inspect environment variables like VERCEL_GIT_COMMIT_REF, GITHUB_BRANCH, or HEAD for crafted Git branch names containing quotes. Review generated client modules for unexpected code injection in packages/@tinacms/cli/src/next/codegen/

Impact Analysis

If exploited, this vulnerability could allow an attacker to read sensitive environment credentials, modify deployment artifacts, or make unauthorized network requests. The impact depends on the privileges of the build process and the sensitivity of the data involved. Systems using affected versions of @tinacms/cli for preview builds are at risk.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, which may violate compliance requirements under GDPR, HIPAA, or other regulations. Exposure of environment credentials or modification of deployment artifacts could result in data breaches or integrity violations, triggering regulatory penalties or legal consequences.

Mitigation Strategies

Upgrade to Tina CMS version 3.0.0 or later immediately. Remove or sanitize untrusted Git branch names before they are used in environment variables. Audit deployment artifacts for signs of compromise and revoke any exposed credentials.

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