# CVE-2026-126774: @tinacms/mdx before 2.4.2 Code Injection via MDX Serializer Rich-Text Values

Status: published. Published: 2026-11-11. Updated: 2026-11-11.

@tinacms/mdx before 2.4.2 contains a code injection vulnerability in its MDX serializer, which writes rich-text values into MDX expressions without escaping them. Authenticated content editors can save crafted values that break out of list field or highlightColor expressions in the stored .mdx file, executing JavaScript in visitors' browsers or on build and server-side rendering hosts.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/tinacms/tinacms/pull/7958
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/tinacms/tinacms/commit/19285c6deeee52c380e8b2fdeafedc9530dc0618

## Affected products and versions

- tinacms / @tinacms/mdx (%40tinacms/mdx): ≥ 0; < 2.4.2 (affected, semver); 2.4.2 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.8 (high); CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 8.2 (high); CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-94

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/tinacms/tinacms/security/advisories/GHSA-6vw5-w22x-ghxv (CNA: VulnCheck; vendor-advisory)

- https://github.com/tinacms/tinacms/pull/7958 (CNA: VulnCheck; patch, issue-tracking)

- https://github.com/tinacms/tinacms/commit/19285c6deeee52c380e8b2fdeafedc9530dc0618 (CNA: VulnCheck; patch)

- https://github.com/tinacms/tinacms/releases/tag/%40tinacms/mdx%402.4.2 (CNA: VulnCheck; release-notes)

- https://github.com/tinacms/tinacms/blob/%40tinacms/mdx%400.60.3/packages/%40tinacms/mdx/src/stringify/acorn.ts#L81 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/tinacms-mdx-before-2.4.2-code-injection-via-mdx-serializer-rich-text-values (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-126774; retrieved 2026-11-11; source updated 2026-11-11

Revision: 2651b3ffc967a2de9bdad65c0bab173bd41ace011f4fecd3d9caec087695acd1

Canonical: https://y2.dev/cve/CVE-2026-126774

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- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

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