CVE-2026-55085: Ether Etherpad

Critical severity, CVSS 9.6. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Ether Etherpad: before 3.3.1 (fixed in 3.3.1)

Published 2026-08-19. Last modified 2026-09-09.