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.

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.

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:

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)>}

or

import { convertLatexToMarkup } from 'mathlive';
document.body.innerHTML = convertLatexToMarkup('\\text{<img src=x onerror=alert(1)>}');

Impact

MathLive users who render untrusted mathematical expressions can encounter malicious input that runs arbitrary JavaScript.

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.

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.

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:

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)>}

or

import { convertLatexToMarkup } from 'mathlive';
document.body.innerHTML = convertLatexToMarkup('\\text{<img src=x onerror=alert(1)>}');

Impact

MathLive users who render untrusted mathematical expressions can encounter malicious input that runs arbitrary JavaScript.