mathlive's Lack of Escaping of HTML allows for XSS

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

EPSS

• CVE-2026-54705: 0.30% estimated exploitation activity in the next 30 days; percentile 22.70 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

29 Jul 2026, 17:21 UTC

Last modified by the source

29 Jul 2026, 17:21 UTC

Source last checked

26 Oct 2026, 13:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fm7p-gw32-828p

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# Patch Next advisory brief: CVE-2026-54705

Advisory: mathlive's Lack of Escaping of HTML allows for XSS
IDs: CVE-2026-54705, GHSA-fm7p-gw32-828p
Record: https://patchnext.com/advisories/cve-2026-54705 (revision 1, source checked 26 Oct 2026, 13:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mathlive 0.110.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm mathlive: affected <= 0.109.2; fixed in 0.110.0

## Suggested inspection (read-only)
- `npm ls mathlive --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mathlive.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fm7p-gw32-828p (GitHub-reviewed advisory GHSA-fm7p-gw32-828p lists affected ranges: npm mathlive >=0 <=0.109.2)

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