What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-19 · updated 2026-10-24
• Weakness: CWE-863

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

• etherpad: from 2.1.0, < 3.1.0

References

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

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