Vulnerability · Published Aug 19, 2026 · Assigned by GitHub_M

CVE-2026-55089Etherpad: JWT `admin` claim presence-only check lets non-admin OAuth users invoke every Etherpad HTTP API endpoint

Critical 9.9

In plain English

A critical-severity incorrect authorization in etherpad from ether. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities).

Severity (CVSS 3.1)9.9Critical

Exploit odds (30 days)0.5%top 59.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

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.

Affected products (as reported)

Vendor	Product	Versions
ether	etherpad	>= 2.1.0, < 3.1.0

Weakness: CWE-863 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L

References

https://github.com/ether/etherpad/security/advisories/GHSA-qfmh-fph3-mw8q x_refsource_CONFIRM
https://github.com/ether/etherpad/pull/7784 x_refsource_MISC
https://github.com/ether/etherpad/commit/8c6104c5d5daf41f0d454acc04d42dffa0e0d996 x_refsource_MISC
https://github.com/ether/etherpad/releases/tag/v3.1.0 x_refsource_MISC