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CVE-2026-55090— Etherpad: Stored XSS in HTML export via unescaped attribute-pool values

Quick assessment

Affected
ether etherpad
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

etherpad是ETHER组织的一个支持多人实时在线协作的文档编辑工具。 ETHER etherpad 3.3.0之前版本存在跨站脚本漏洞，该漏洞源于getHTMLFromAtext将exportHtmlAdditionalTagsWithData插件钩子中的值插入span数据属性时缺少HTML属性转义，可能导致存储型跨站脚本攻击。

CVSS 5.3 · Medium EPSS 0.54% · P43

Affected Version Matrix 1

VendorProduct Version RangeStatus
ether etherpad < 3.3.0 affected
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I. Basic Information for CVE-2026-55090

Vulnerability Information
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Vulnerability Title
Etherpad: Stored XSS in HTML export via unescaped attribute-pool values
Source: CVE Program / CVE List V5
Vulnerability Description
Etherpad is a real-time collaborative editor. Prior to 3.3.0, getHTMLFromAtext in src/node/utils/ExportHtml.ts interpolates values from the exportHtmlAdditionalTagsWithData plugin hook into span data attributes without HTML attribute escaping. A pad editor can place an attacker-controlled value into the attribute pool through moveOpsToNewPool and AttributePool.putAttrib. When a bundled plugin such as ep_font_color or ep_font_size registers the hook, opening the resulting HTML export causes the value to execute as stored cross-site scripting in the Etherpad origin. This issue is fixed in version 3.3.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
ETHER etherpad 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
etherpad是ETHER组织的一个支持多人实时在线协作的文档编辑工具。 ETHER etherpad 3.3.0之前版本存在跨站脚本漏洞，该漏洞源于getHTMLFromAtext将exportHtmlAdditionalTagsWithData插件钩子中的值插入span数据属性时缺少HTML属性转义，可能导致存储型跨站脚本攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
ether etherpad < 3.3.0 -

II. Public POCs for CVE-2026-55090

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III. Intelligence Information for CVE-2026-55090

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Patches & Fixes for CVE-2026-55090 (2)

Vendor Advisories for CVE-2026-55090 (1)

Vendor Pages for CVE-2026-55090 (1)

Same Patch Batch · ether · 2026-08-19 · 6 CVEs total

CVE-2026-55089 9.9 CRITICAL Etherpad: JWT `admin` claim presence-only check lets non-admin OAuth users invoke every Et
CVE-2026-55085 9.6 CRITICAL Etherpad: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripti
CVE-2026-55088 6.8 MEDIUM Etherpad: Device-to-device author-token transfer endpoint is replayable, never expires, an
CVE-2026-55087 6.1 MEDIUM Etherpad: x-proxy-path header reflected into admin HTML/JS/CSS (cache-poisoning XSS) and c
CVE-2026-55086 4.2 MEDIUM Etherpad: Import/export use Math.random() for temp file paths; predictable paths on shared

IV. Related Vulnerabilities

Same product: etherpad
Same vendor: ether
Same weakness: CWE-79

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