CVE-2026-55085Public exploitNetwork attack vectorHinoki check available

Stored XSS via unescaped list start

Published Aug 19, 2026 · Updated Aug 19, 2026

Stored XSS in Etherpad before 3.3.1 allows attackers to execute script in other users' browsers via a crafted .etherpad import. result.appendSpan in src/static/js/domline.ts writes the numbered-list start value into an unquoted ol start attribute and then into node.innerHTML, while ImportEtherpad.setPadRaw accepts attacker-controlled attribute-pool values from imported .etherpad files without validating start. Exploitation requires write access to a pad and a victim opening the pad or /timeslider; on default public pads, ordinary anonymous write access is enough, and an administrator who views the pad exposes the same-origin admin session to attacker JavaScript.

CVSS severity9.6
Critical
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Stored XSS in Etherpad before 3.3.1 allows attackers to execute script in other users' browsers via a crafted .etherpad import. result.appendSpan in src/static/js/domline.ts writes the numbered-list start value into an unquoted ol start attribute and then into node.innerHTML, while ImportEtherpad.setPadRaw accepts attacker-controlled attribute-pool values from imported .etherpad files without validating start. Exploitation requires write access to a pad and a victim opening the pad or /timeslider; on default public pads, ordinary anonymous write access is enough, and an administrator who views the pad exposes the same-origin admin session to attacker JavaScript.

The record

CVE
CVE-2026-55085
Published
Aug 19, 2026
Updated
Aug 19, 2026
Vendor
Etherpad Foundation
Product
Etherpad
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Etherpad Foundation · Etherpadversion=< 3.3.1

Published CVSS scores

9.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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