Is CVE-2026-126774 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-126774 being exploited in the wild.

How severe is CVE-2026-126774?

High severity, with a CVSS score of 8.2, published 11 November 2026.

Which products and versions are affected?

TinaCMS @Tinacms/Mdx before 2.4.2.

Is there a fix for CVE-2026-126774?

Yes: fixed in @tinacms/mdx 2.4.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-126774 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-126774?

Check whether you run TinaCMS @Tinacms/Mdx at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-126774: @tinacms/mdx code injection in MDX serializer

CVE-2026-126774 · Severity: high · CVSS 8.2 · Published 2026-11-11

@tinacms/mdx is a library that converts content into MDX format for rendering rich-text documents in web applications. The library fails to escape user-supplied values when writing them into MDX expressions, allowing authenticated content editors to inject malicious JavaScript code. When visitors view the affected content or build systems process it, the injected code executes in their browsers or servers.

Vendors: TinaCMS.

Quick answers

Is CVE-2026-126774 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-126774 being exploited in the wild.
How severe is CVE-2026-126774?: High severity, with a CVSS score of 8.2, published 11 November 2026.
Which products and versions are affected?: TinaCMS @Tinacms/Mdx before 2.4.2.
Is there a fix for CVE-2026-126774?: Yes: fixed in @tinacms/mdx 2.4.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-126774 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-126774?: Check whether you run TinaCMS @Tinacms/Mdx at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: @tinacms/mdx 2.4.2

Technical details

A code injection vulnerability exists in the MDX serializer component where rich-text field values (such as list fields and highlightColor expressions) are written into MDX expressions without proper escaping. An authenticated content editor can craft malicious values that break out of the expression context and inject arbitrary JavaScript. The injected code executes during client-side rendering, server-side rendering, or build-time processing depending on deployment configuration.

Affected products

TinaCMS @tinacms/mdx before 2.4.2

Timeline

2026-11-11: disclosed

References

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