---
cve: "CVE-2026-55087"
severity: "MEDIUM"
cvss: 6.1
epss: "57%"
vendor: "ether"
kev: false
exploited: false
published: "2026-08-19 20:17:17"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-02T13:20:42+02:00"
---

# CVE-2026-55087

> 6.1 MEDIUM · 🧪 PoC

## Beschreibung

Etherpad is a real-time collaborative editor. From 2.1.0 until 3.1.0, Etherpad uses the attacker-controlled x-proxy-path request header in src/node/hooks/express/admin.ts when substituting paths into HTML, JavaScript, and CSS under /admin without sanitization, Vary: x-proxy-path, or Cache-Control: private, no-store. A shared proxy or CDN can cache the resulting response and serve attacker-injected script to an administrator. In src/node/hooks/express/specialpages.ts, version 3.0.0 also accepts a protocol-relative x-proxy-path value when constructing the /p/:pad/timeslider redirect, allowing redirection to an attacker-controlled host. The issues are exploitable when the deployment permits client-supplied x-proxy-path headers to reach Etherpad. This issue is fixed in version 3.1.0.

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Erforderlich | good |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Gering | warn |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 8c6104c5d5daf41f0d454acc04d42dffa0e0d996 (Commit)

## Referenzen

- <https://github.com/ether/etherpad/security/advisories/GHSA-fjgc-3mj7-8rg8>
- <https://github.com/ether/etherpad/pull/7784>
- <https://github.com/ether/etherpad/commit/8c6104c5d5daf41f0d454acc04d42dffa0e0d996>
- <https://github.com/ether/etherpad/tree/3.1.0>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-55087) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_