Cross-Site Scripting (XSS) in Etherpad (CVE-2026-55085)
Summary
Cross-site scripting in Etherpad (CVE-2026-55085). Confidential information can be exposed externally.
Original description
The description as published by the source.
Etherpad is a real-time collaborative editor. Prior to 3.3.1, result.appendSpan in src/static/js/domline.ts interpolates the start attribute of a numbered list directly into an unquoted ol start attribute before assigning the generated markup to node.innerHTML. ImportEtherpad.setPadRaw in src/node/utils/ImportEtherpad.ts accepts attacker-controlled attribute-pool values from a crafted .etherpad import, including list:number1 and a malicious start value. Any user with write access to a pad can store markup that executes as cross-site scripting when another user opens the pad or /timeslider, including when an administrator views the pad. This issue is fixed in version 3.3.1.
Source: NIST National Vulnerability Database NVD
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-2026-55085 has been found in Etherpad.
Confidential information can be exposed externally. CVSS score: 9.6/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Etherpad CVE-2026-55085" on the vendor's site.
CVE-2026-55085 (Etherpad) — CWE-79 / CVSS v3 9.6
Attack vector: remote (network-reachable) / unauthenticated
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 Etherpad.
Check the vendor advisory for the affected versions of Etherpad.
Severity: Critical (CVSS 9.6/10). Confidential information can be exposed externally.
Update to the patched release per vendor advisory.
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 'Etherpad' . 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
-
1Identify exposure identify
grep -r 'Etherpad' . | 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
Etherpadを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-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。