CVE-2026-55087

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 v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

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

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-19 20:17

Updated : 2026-09-09 21:15

NVD link : CVE-2026-55087

Mitre link : CVE-2026-55087

CVE.ORG link : CVE-2026-55087

JSON object : View

Products Affected

No product.

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE-444

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CWE-601

URL Redirection to Untrusted Site ('Open Redirect')

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