high

CVE-2026-55090

npm · ep_etherpad-lite

Summary

Etherpad has stored XSS in HTML export via unescaped attribute-pool values

Severity
high
EPSS
0.5% (p46)
CWE
CWE-79
Also known as
GHSA-2jp7-wwpg-3p9w
Published
2026-08-17
Updated
2026-08-17

Advisory details

Fix: PR #7905 (ether/etherpad).

getHTMLFromAtext in src/node/utils/ExportHtml.ts interpolates values from the exportHtmlAdditionalTagsWithData plugin hook into span data-<k>="<v>" without HTML-attribute escaping. The value comes verbatim from the pad attribute pool, which a pad editor controls via a crafted changeset (only author attributes are validated; moveOpsToNewPool -> AttributePool.putAttrib stores any value). With a bundled plugin that registers the hook (ep_font_color / ep_font_size), an attribute value such as " onload="alert(1) is exported as <span data-color="" onload="alert(1)"> and served as text/html, yielding stored XSS for any collaborator who opens the export.

Fix: escape the name and value via Security.escapeHTMLAttribute. PR #7905 also adds a startup warning when default/placeholder account or SSO credentials are configured (defense-in-depth, non-breaking).

References

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.