GHSA-2JP7-WWPG-3P9W

Vulnerability from github – Published: 2026-08-17 17:49 – Updated: 2026-08-17 17:49
VLAI
Summary
Etherpad has stored XSS in HTML export via unescaped attribute-pool values
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).

Severity
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.8.14"
      },
      "package": {
        "ecosystem": "npm",
        "name": "ep_etherpad-lite"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55090"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-17T17:49:38Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "Fix: PR #7905 (ether/etherpad).\n\n`getHTMLFromAtext` in `src/node/utils/ExportHtml.ts` interpolates values from the `exportHtmlAdditionalTagsWithData` plugin hook into `span data-\u003ck\u003e=\"\u003cv\u003e\"` 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` -\u003e `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 `\u003cspan data-color=\"\" onload=\"alert(1)\"\u003e` and served as text/html, yielding stored XSS for any collaborator who opens the export.\n\nFix: 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).",
  "id": "GHSA-2jp7-wwpg-3p9w",
  "modified": "2026-08-17T17:49:39Z",
  "published": "2026-08-17T17:49:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ether/etherpad/security/advisories/GHSA-2jp7-wwpg-3p9w"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ether/etherpad/pull/7905"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ether/etherpad/commit/86c56cf827dd6e5ff1b6cd3760f87adc47f58bb1"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ether/etherpad"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ether/etherpad/releases/tag/3.3.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Etherpad has stored XSS in HTML export via unescaped attribute-pool values"
}



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