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High, CVSS 8.7amended

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

CVE-2026-55090GHSA-2jp7-wwpg-3p9w

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (ep_etherpad-lite 3.3.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.7 · 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 · score source
EPSS
  • CVE-2026-55090: 0.55% estimated exploitation activity in the next 30 days; percentile 45.91 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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 (epfontcolor / epfontsize), 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).

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-2jp7-wwpg-3p9w

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-2jp7-wwpg-3p9w

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-55090

Advisory: Etherpad has stored XSS in HTML export via unescaped attribute-pool values
IDs: CVE-2026-55090, GHSA-2jp7-wwpg-3p9w
Record: https://patchnext.com/advisories/cve-2026-55090 (revision 3, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ep_etherpad-lite 3.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm ep_etherpad-lite: affected <= 1.8.14; fixed in 3.3.0

## Suggested inspection (read-only)
- `npm ls ep_etherpad-lite --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 ep_etherpad-lite.
- 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://osv.dev/vulnerability/GHSA-2jp7-wwpg-3p9w (OSV record GHSA-2jp7-wwpg-3p9w lists affected ranges: npm ep_etherpad-lite >=0 <3.3.0 (fixed))
- Verified: https://github.com/advisories/GHSA-2jp7-wwpg-3p9w (GitHub-reviewed advisory GHSA-2jp7-wwpg-3p9w lists affected ranges: npm ep_etherpad-lite >=0 <=1.8.14)

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