CVE-2026-55089

CRITICALPre-NVD 9.99.9
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This critical-severity CVE scores 9.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (38th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated
9.9EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.9Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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
9.9CRITICALmedium confidence
EG Risk
61
EG Risk 61/100

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 (value × EchelonGraph’s weight)
Severity99% × 45%
The EG Score, 9.9 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
38th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 19, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Oct 7, 2026
Patch available. Sources: github_release, github, github_commit, github_pr.
GitHub advisoryMentions a patch (unverified)

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 pull request 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 14× in last 7d / 56× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 105 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 5 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-14 08:52 UTCEG score recompute
  2. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
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  9. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  10. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
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  18. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 37th percentile
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  1. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  2. 2026-09-30 20:34 UTCEG score recompute
  3. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  4. 2026-09-30 08:39 UTCEG score recompute
  5. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  6. 2026-09-28 21:41 UTCEG score recompute
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  8. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  9. 2026-09-27 16:09 UTCEG score recompute
  10. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
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  12. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 37th percentile
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  14. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 37th percentile
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  16. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  17. 2026-09-22 19:49 UTCEG score recompute
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  20. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  21. 2026-09-19 18:31 UTCEG score recompute
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  23. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  24. 2026-09-17 21:29 UTCEG score recompute
  25. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  26. 2026-09-16 14:57 UTCEG score recompute
  27. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 37th percentile
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  29. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 37th percentile
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  32. 2026-09-13 18:01 UTCEG score recompute
  33. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  34. 2026-09-12 15:33 UTCEG score recompute
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  36. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  37. 2026-09-11 12:59 UTCEG score recompute
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  39. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  40. 2026-09-09 02:32 UTCEG score recompute
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  49. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.4% · 28th percentile
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  54. 2026-09-01 08:17 UTCEG score recompute
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  60. 2026-08-29 01:47 UTCEG score recompute
  61. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.4% · 28th percentile
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  68. 2026-08-24 17:34 UTCEG score recompute
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  71. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.4% · 28th percentile
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  73. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  74. 2026-08-21 02:35 UTCEG score recompute
  75. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.4% · 28th percentile

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Frequently asked(5)

What is CVE-2026-55089?
CVE-2026-55089 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-55089 published?
The CVE record for CVE-2026-55089 was published on August 19, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 9, 2026; the record at its source may have been updated since.
Is CVE-2026-55089 actively exploited?
CVE-2026-55089 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (38th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55089?
CVE-2026-55089 has a CVSS base score of 9.9 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55089?
A fix for CVE-2026-55089 is available: update to the fixed version the vendor names in its advisory.

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