{"id":"GHSA-fm7p-gw32-828p","summary":"mathlive's Lack of Escaping of HTML allows for XSS","details":"### Summary\n\nDespite 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.\n\n### Details\n\n`Box.toMarkup` at `src/core/box.ts:356` concatenates `this.value` into the rendered span without HTML-escaping. In text mode any literal character (`\u003c`, `\u003e`, `&`, `\"`) 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.\n\nBoth outputs flow into `innerHTML` sinks via the public API. `\u003cmath-span\u003e` / `\u003cmath-div\u003e` (`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`).\n\n### PoC\n\n1. Go to https://mathlive.io/mathfield/demo/\n2. open DevTools console and paste:\n\n```js\nconst s = document.createElement('math-span');\ns.style.display = 'block';\ns.textContent = '\\\\text{\u003cimg src=x onerror=alert(1)\u003e}';\ndocument.body.appendChild(s);\ns.scrollIntoView();\n```\n\nEquivalent payloads: `\\mbox{\u003cimg src=x onerror=alert(1)\u003e}`\n\nor\n\n```js\nimport { convertLatexToMarkup } from 'mathlive';\ndocument.body.innerHTML = convertLatexToMarkup('\\\\text{\u003cimg src=x onerror=alert(1)\u003e}');\n```\n\n### Impact\n\nMathLive users who render untrusted mathematical expressions can encounter malicious input that runs arbitrary JavaScript.","aliases":["CVE-2026-54705"],"modified":"2026-07-29T17:41:44.693943Z","published":"2026-07-29T17:21:26Z","database_specific":{"nvd_published_at":null,"cwe_ids":["CWE-116"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-07-29T17:21:26Z"},"references":[{"type":"WEB","url":"https://github.com/arnog/mathlive/security/advisories/GHSA-fm7p-gw32-828p"},{"type":"WEB","url":"https://github.com/arnog/mathlive/issues/3028"},{"type":"WEB","url":"https://github.com/arnog/mathlive/commit/5fe1c46153883f9ec0249a5c8c34e64aaae9cfb8"},{"type":"PACKAGE","url":"https://github.com/arnog/mathlive"}],"affected":[{"package":{"name":"mathlive","ecosystem":"npm","purl":"pkg:npm/mathlive"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.110.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-fm7p-gw32-828p/GHSA-fm7p-gw32-828p.json","last_known_affected_version_range":"\u003c= 0.109.2"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L"}]}