CVE-2026-55089

CRITICALPre-NVD 9.99.9—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 72% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
9.9EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.9Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
9.9
EG Score
9.9(medium)
EG Risk
61(Track*)
EG Risk 61/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity99% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

August 19, 2026

Last Modified

August 19, 2026

Advisory Details (4)

Auto-updated Aug 26, 2026
🔬 Proof of concept available. Patch available. Sources: github_pr, github_release, github, github_commit.
github Patch Available🟡 PoC Available

JWT `admin` claim presence-only check lets non-admin OAuth users invoke every Etherpad HTTP API endpoint · Advisory · ether/etherpad · GitHub

https://github.com/ether/etherpad/security/advisories/GHSA-qfmh-fph3-mw8q
github_release Patch Available

v3.1.0

Patch available: ether/etherpad v3.1.0

https://github.com/ether/etherpad/releases/tag/v3.1.0
github_pr Patch Available

harden: assorted server-side tightening for 3.0.2

Patch available: ether/etherpad v3.1.0 (PR #7784 merged 2026-05-17)

https://github.com/ether/etherpad/pull/7784
github_commit Patch Available

commit 8c6104c5d5da (ether/etherpad)

Patch available: ether/etherpad v3.1.0 (contains commit 8c6104c5d5da)

https://github.com/ether/etherpad/commit/8c6104c5d5daf41f0d454acc04d42dffa0e0d996

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 23× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 01:32 UTCEG score recompute
  2. 2026-08-30 01:22 UTCEPSS rescore
  3. 2026-08-29 01:47 UTCEG score recompute
  4. 2026-08-28 21:41 UTCEPSS rescore
  5. 2026-08-27 18:44 UTCEG score recompute
  6. 2026-08-27 14:25 UTCEPSS rescore
  7. 2026-08-26 15:16 UTCEG score recompute
  8. 2026-08-26 14:46 UTCEPSS rescore
  9. 2026-08-25 16:28 UTCEG score recompute
  10. 2026-08-25 13:49 UTCEPSS rescore
  11. 2026-08-24 17:34 UTCEG score recompute
  12. 2026-08-24 10:01 UTCEG score recompute
  13. 2026-08-23 03:44 UTCEG score recompute
  14. 2026-08-23 00:19 UTCEPSS rescore
  15. 2026-08-22 01:16 UTCEG score recompute
  16. 2026-08-21 23:49 UTCEPSS rescore
  17. 2026-08-21 02:35 UTCEG score recompute
  18. 2026-08-20 22:55 UTCEPSS rescore
  19. 2026-08-20 00:07 UTCEG score recompute
  20. 2026-08-19 20:20 UTCEG score recompute
  21. 2026-08-19 19:58 UTCEG score recompute
  22. 2026-08-19 19:43 UTCEG score recompute
  23. 2026-08-19 19:42 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55089?
CVE-2026-55089 is a critical vulnerability published on August 19, 2026. 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…
When was CVE-2026-55089 disclosed?
CVE-2026-55089 was first published in the National Vulnerability Database on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55089 actively exploited?
CVE-2026-55089 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 71.7% of all scored CVEs.
What is the CVSS score of CVE-2026-55089?
CVE-2026-55089 has a CVSS v3 base score of 9.9 (NVD).
How do I remediate CVE-2026-55089?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55089, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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