CVE-2026-55089 — CRITICAL (9.9)

Vulnerability Description

Etherpad is a real-time collaborative editor. From 2.1.0 until 3.1.0, Etherpad's src/node/handler/APIHandler.ts authorizes requests to /api/2/* in the authorization_code OAuth path by using requiredClaims with the admin claim. This check requires only that the claim exists, while src/node/security/OAuth2Provider.ts issues admin: false for configured non-admin users. A non-admin user with a valid signed token can therefore invoke administrative functions including setHTML, setText, appendText, deletePad, copyPad, movePad, restoreRevision, anonymizeAuthor, listAllPads, and listAuthorsOfPad, allowing disclosure, modification, or deletion of pads across the instance. This issue is fixed in version 3.1.0.

CVSS Score

9.9

CRITICAL

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

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

LOW

Related Weaknesses (CWE)

CWE-863

References

FAQ

What is CVE-2026-55089?

CVE-2026-55089 is a vulnerability with a CVSS score of 9.9 (CRITICAL). Etherpad is a real-time collaborative editor. From 2.1.0 until 3.1.0, Etherpad's src/node/handler/APIHandler.ts authorizes requests to /api/2/* in the authorization_code OAuth path by using requiredCl...

How severe is CVE-2026-55089?

CVE-2026-55089 has been rated CRITICAL with a CVSS base score of 9.9/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2026-55089?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.