CVE-2026-55089 Etherpad: JWT `admin` claim presence-only check lets non-admin OAuth users invoke every Etherpad HTTP API endpoint
Non-admin OAuth users can invoke administrative API endpoints due to a flawed JWT claim check, allowing unauthorized pad access and modification.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-55089?
CVE-2026-55089 is a critical missing authorization vulnerability in etherpad, published on 19 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-863
Which versions are affected by CVE-2026-55089?
How do I fix CVE-2026-55089?
No fix has been published for CVE-2026-55089 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-55089 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55089 exists.
Sources
Also known as GHSA-qfmh-fph3-mw8q.