Bug 2571858 (CVE-2026-126774)

Summary: CVE-2026-126774 @tinacms/mdx: @tinacms/mdx: Arbitrary code execution via unescaped rich-text expressions
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in @tinacms/mdx. This vulnerability allows arbitrary code execution because the MDX serializer writes rich-text values into expressions without proper escaping. An authenticated content editor can exploit this flaw by submitting crafted values into stored content fields. Consequently, the injected code is executed within visitors' web browsers or on backend build and server-side rendering systems.
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Description OSIDB Bzimport 2026-11-11 18:51:12 UTC
@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.