Summary
Unsanitized JavaScript code injection possible in gatsby-plugin-mdx
Workarounds
If an older version of gatsby-plugin-mdx must be used, input passed into the plugin should be sanitized ahead of processing.
We encourage projects to upgrade to the latest major release branch for all Gatsby plugins to ensure the latest security updates and bug fixes are received in a timely manner.
Credits
We would like to thank Snyk [snyk.io] for initially bringing the issue to our attention, as well as Feng Xiao and Zhongfu Su, who reported the issue to Snyk.
For more information
Email us at [email protected].
Impact
The gatsby-plugin-mdx plugin prior to versions 3.15.2 and 2.14.1 passes input through to the gray-matter npm package, which is vulnerable to JavaScript injection in its default configuration, unless input is sanitized. The vulnerability is present when passing input in both webpack (MDX files in src/pages or MDX file imported as component in frontend / React code) and data mode (querying MDX nodes via GraphQL). Injected JavaScript executes in the context of the build server.
To exploit this vulnerability untrusted/unsanitized input would need to be sourced or added into an MDX file. The following MDX payload demonstrates a vulnerable configuration:
---js
((require("child_process")).execSync("id >> /tmp/rce"))
---
Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.
CVE-2022-25863 has a CVSS score of 8.1 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.14.1, 3.15.2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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A patch has been introduced in [email protected] and [email protected] which mitigates the issue by disabling the gray-matter JavaScript Frontmatter engine. The patch introduces a new option, JSFrontmatterEngine which is set to false by default. When setting JSFrontmatterEngine to true, input passed to gatsby-plugin-mdx must be sanitized before processing to avoid a security risk. Warnings are displayed when enabling JSFrontmatterEngine to true or if it appears that the MDX input is attempting to use the Frontmatter engine.
Frequently Asked Questions
- What is CVE-2022-25863? CVE-2022-25863 is a high-severity insecure deserialization vulnerability in gatsby-plugin-mdx (npm), affecting versions < 2.14.1. It is fixed in 2.14.1, 3.15.2. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
- How severe is CVE-2022-25863? CVE-2022-25863 has a CVSS score of 8.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of gatsby-plugin-mdx are affected by CVE-2022-25863? gatsby-plugin-mdx (npm) versions < 2.14.1 is affected.
- Is there a fix for CVE-2022-25863? Yes. CVE-2022-25863 is fixed in 2.14.1, 3.15.2. Upgrade to this version or later.
- Is CVE-2022-25863 exploitable, and should I be worried? Whether CVE-2022-25863 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2022-25863 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2022-25863?
- Upgrade
gatsby-plugin-mdxto 2.14.1 or later - Upgrade
gatsby-plugin-mdxto 3.15.2 or later
- Upgrade