gatsby-transformer-remark has possible unsanitized JavaScript code injection
Date: 2023-01
Affected: npm/gatsby-transformer-remark, npm/gatsby-transformer-remark
Attack vector: rce
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2023-22491
CWE: CWE-20
CWE-79
CVSS: 8.1 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N)

### Impact The gatsby-transformer-remark plugin prior to versions 5.25.1 and 6.3.2 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 in gatsby-transformer-remark when passing input in data mode (querying MarkdownRemark 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 by or added into a file processed by gatsby-transformer-remark. The following payload demonstrates a vulnerable configuration: ``` ---js ((require("child_process")).execSync("id >> /tmp/rce")) --- ``` ### Patches A patch has been introduced in `gatsby-transformer-remark@5.25.1` and `gatsby-transformer-remark@6.3.2` 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 MarkdownRemark input is attempting to use the Frontmatter engine. ### Workarounds If an older version of `gatsby-transformer-remark` must be used, input passed into the plugin should be sanitized ahead of processing. **We encourag


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