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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-55085
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-19 20:17:17 UTC
Updated2026-08-21 20:16:37 UTC
DescriptionEtherpad 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.

Risk And Classification

Primary CVSS: v3.1 9.6 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

EPSS: 0.003620000 probability, percentile 0.295280000 (date 2026-08-20)

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.6CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L
3.1CNADECLARED9.6CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Ether Etherpad affected < 3.3.1 Not specified

References

ReferenceSourceLinkTags
github.com/ether/etherpad/pull/7937 [email protected] github.com
github.com/ether/etherpad/security/advisories/GHSA-f7h5-v9hm-548j 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/ether/etherpad/commit/d828185efcac9abc2e46e6da1c171393500fa319 [email protected] github.com
github.com/ether/etherpad/releases/tag/v3.3.1 [email protected] github.com
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