CVE-2026-55090 Etherpad: Stored XSS in HTML export via unescaped attribute-pool values
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-55090?
CVE-2026-55090 is a medium-severity vulnerability in etherpad, published on 19 Aug 2026.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-55090?
2 open source packages ship an affected version, including ep_etherpad-lite.
| Package | Affected | Fixed in |
|---|---|---|
ep_etherpad-lite npm | All versions | 3.3.0 |
ep_etherpad-lite npm | All versions | 3.3.0 |
How do I fix CVE-2026-55090?
Upgrade ep_etherpad-lite to 3.3.0 or later.
Is CVE-2026-55090 being exploited?
There is no known exploitation of CVE-2026-55090 in the wild and no public exploit code.
Sources
Also known as GHSA-2jp7-wwpg-3p9w.