CyberSecBulletin
CVE-2026-126774NVD status: Awaiting Analysis

@tinacms/mdx: Improper Control of Generation of Code

Published Updated By the CyberSecBulletin desk

CVE-2026-126774 is a high-severity improper control of generation of code vulnerability in @tinacms/mdx from Tinacms, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 2.4.2 as the first without the flaw, so updating @tinacms/mdx to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.37% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update @tinacms/mdx to 2.4.2 or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Tinacms@tinacms/mdxbefore 2.4.22.4.2

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N. Scored by CNA (vulncheck.com).

Scoring systemScoreSeverityScored by
CVSS 4.08.8HighCNA (vulncheck.com)
CVSS 3.18.2HighCNA (vulncheck.com)

Official description

@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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Control of Generation of Code

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.

How developers prevent this class of flaw

  • Refactor your program so that you do not have to dynamically generate code.
  • Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
  • Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

More Improper Control of Generation of Code vulnerabilities (CWE-94)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Improper Control of Generation of Code vulnerabilities

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