fkie_cve-2026-54705

MathLive provides web components for math display and input. Prior to 0.110.0, MathLive fails to escape text-mode content in \text{} and \mbox{} commands in Box.toMarkup at src/core/box.ts, in xmlEscape, scanText, and text-mode output in src/formats/atom-to-math-ml.ts, and through convertLatexToMarkup, convertLatexToMathMl, <math-span>, <math-div>, and the default identity MathfieldElement.createHTML, allowing malicious input to run arbitrary JavaScript when rendered. This issue is fixed in version 0.110.0.

GHSA-fm7p-gw32-828p — mathlive's Lack of Escaping of HTML allows for XSS

Affected: npm: mathlive

### Summary

Despite the 0.104.0 patch escaping attribute-bearing constructs (`\htmlData`, `\href`), text-content reflection was missed. The `\text{}`, `\mbox{}` commands accept arbitrary characters in their body and emit them raw and unescaped into both the HTML markup and the MathML output, leading to XSS.

### Details

`Box.toMarkup` at `src/core/box.ts:356` concatenates `this.value` into the rendered span without HTML-escaping. In text mode any literal character (`<`, `>`, `&`, `"`) is wrapped into a `TextAtom` whose `value` is the raw codepoint and lands in the markup unchanged. The MathML serializer at `src/formats/atom-to-math-ml.ts` is independently broken: `xmlEscape` deliberately omits the `&` rule, and `scanText`, `case 'text'`, and the `mode === 'text'` early return all emit `atom.value` raw.

Both outputs flow into `innerHTML` sinks via the public API. `<math-span>` / `<math-div>` (`src/public/math-static-elements.ts:331,407`) bypass `MathfieldElement.createHTML` entirely. The editor and SSR paths route through `createHTML`, but its default value is the identity function (`src/public/mathfield-element.ts:789`).

### PoC

1. Go to https://mathlive.io/mathfield/demo/ 2. open DevTools console and paste:

```js const s = document.createElement('math-span'); s.style.display = 'block'; s.textContent = '\\text{<img src=x onerror=alert(1)>}'; document.body.appendChild(s); s.scrollIntoView(); ```

Equivalent payloads: `\mbox{<img src=x onerror=alert(1)>}`

```js impo…

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fkie_cve-2026-54705

GHSA-fm7p-gw32-828p — mathlive's Lack of Escaping of HTML allows for XSS