Cross-Site Scripting (XSS) in ep_etherpad-lite (CVE-2026-55090)
Summary
Cross-site scripting in ep_etherpad-lite (CVE-2026-55090). Risk of unauthorized operations or information disclosure. Exploitable via getHTMLFromAtext. Mitigation: upgrade to 3.3.0 or later.
Original description
The description as published by the source.
Fix: PR #7905 (ether/etherpad).
getHTMLFromAtext in src/node/utils/ExportHtml.ts interpolates values from the exportHtmlAdditionalTagsWithData plugin hook into span data-="" 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 `` 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).
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-55090 has been found in ep_etherpad-lite.
Attackers can target a specific entry point like getHTMLFromAtext over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade ep_etherpad-lite to 3.3.0 or later.
If unsure, ask your IT team or search "ep_etherpad-lite CVE-2026-55090" on the vendor's site.
CVE-2026-55090 (ep_etherpad-lite) — CWE-79
Attack surface: getHTMLFromAtext / exportHtmlAdditionalTagsWithData / author / moveOpsToNewPool
Patched: 3.3.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in ep_etherpad-lite. Attackers reach the vulnerable code path via getHTMLFromAtext.
Check the vendor advisory for the affected versions of ep_etherpad-lite. Attack surface: getHTMLFromAtext / exportHtmlAdditionalTagsWithData / author / moveOpsToNewPool.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 3.3.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'ep_etherpad-lite' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'ep_etherpad-lite' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
ep_etherpad-liteを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade ep_etherpad-lite to 3.3.0ステージング環境で 3.3.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web security-advisories@github.com