Vulnerability · Published Aug 19, 2026 · Assigned by GitHub_M

CVE-2026-55085Etherpad: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in etherpad-lite

Critical 9.6

In plain English

A critical-severity cross-site scripting in etherpad from ether. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities).

Severity (CVSS 3.1)9.6Critical

Exploit odds (30 days)0.5%top 58.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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 (as reported)

Vendor	Product	Versions
ether	etherpad	< 3.3.1

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

References

https://github.com/ether/etherpad/security/advisories/GHSA-f7h5-v9hm-548j x_refsource_CONFIRM
https://github.com/ether/etherpad/pull/7937 x_refsource_MISC
https://github.com/ether/etherpad/commit/d828185efcac9abc2e46e6da1c171393500fa319 x_refsource_MISC
https://github.com/ether/etherpad/releases/tag/v3.3.1 x_refsource_MISC