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EUVD-2026-215124

fkie_cve-2025-24981

MDC is a tool to take regular Markdown and write documents interacting deeply with a Vue component. In affected versions unsafe parsing logic of the URL from markdown can lead to arbitrary JavaScript code due to a bypass to the existing guards around the `javascript:` protocol scheme in the URL. The parsing logic implement in `props.ts` maintains a deny-list approach to filtering potential malicious payload. It does so by matching protocol schemes like `javascript:` and others. These security guards can be bypassed by an adversarial that provides JavaScript URLs with HTML entities encoded via hex string. Users who consume this library and perform markdown parsing from unvalidated sources could result in rendering vulnerable XSS anchor links. This vulnerability has been addressed in version 0.13.3 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

GHSA-j82m-pc2v-2484 — Parsed HTML anchor links in Markdown provided to parseMarkdown can result in XSS in @nuxtjs/mdc

Affected: npm: @nuxtjs/mdc

### Summary An unsafe parsing logic of the URL from markdown can lead to arbitrary JavaScript code due to a bypass to the existing guards around the `javascript:` protocol scheme in the URL.

### Details

The parsing logic implement at [https://github.com/nuxt-modules/mdc/blob/main/src/runtime/parser/utils/props.ts#L16](https://github.com/nuxt-modules/mdc/blob/main/src/runtime/parser/utils/props.ts#L16) maintains a deny-list approach to filtering potential malicious payload. It does so by matching protocol schemes like `javascript:` and others.

Specifically, this is the code from the mdc library's parser that is not secure enough:

```js export const unsafeLinkPrefix = [ 'javascript:', 'data:text/html', 'vbscript:', 'data:text/javascript', 'data:text/vbscript', 'data:text/css', 'data:text/plain', 'data:text/xml' ]

export const validateProp = (attribute: string, value: string) => { if (attribute.startsWith('on')) { return false }

if (attribute === 'href' || attribute === 'src') { return !unsafeLinkPrefix.some(prefix => value.toLowerCase().startsWith(prefix)) }

return true } ```

These security guards can be bypassed by an adversarial that provides JavaScript URLs with HTML entities encoded via hex string.

### PoC

The following URL payloads if provided to the markdown parsing library (such as through the usage of `import { parseMarkdown } from '@nuxtjs/mdc/runtime';`) will trigger the alert() dialog:

```markdown # ✅ This is correctly es…