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CriticalVulnerabilityCVE-2026-91637updated 25 Oct 2026, 18:50 UTC

Oracle Essbase flaw lets low-privilege users take over the server

A user with only a basic login can send web requests to Oracle Essbase and gain full control of the system. From there, attackers could also reach other connected products.

Official, 2 sources
SeverityCriticalCVSS 9.9 of 10
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1Low-privilege attackerStarts with a basic valid account
  2. 2HTTP requestSent over the network to Essbase
  3. 3Security flaw exploitedWeakness in the Security component
  4. 4Essbase taken overAttacker gains full control of the instance
  5. ResultAttacker controls Essbase and can affect other products

What happened

A security flaw in the Security component of Oracle Essbase 21.8.3.0.0 is exploitable over HTTP by an attacker holding low-level privileges, leading to complete takeover of the Essbase instance with a scope change that can affect other products.

Why it is dangerous: A successful attack gives full read, change and disruption power over Essbase data and service, and can spread to other systems it connects to. Organizations running Essbase for business analytics and planning are at risk.

Are you affected?

You are affected if you run Oracle Essbase version 21.8.3.0.0 with its HTTP interface reachable from the network.

Oracle Essbase 21.8.3.0.0

What to do

  1. Check whether any Oracle Essbase instance is running version 21.8.3.0.0.
  2. Restrict network access to Essbase HTTP endpoints to trusted users and systems only.
  3. Apply the patch or update from Oracle as soon as it is available for your version.
  4. Review accounts with low-level Essbase access and remove any that are unnecessary.

Timeline

  1. 20 Oct 2026, 22:21 UTC
    Publicly disclosed
  2. 20 Oct 2026, 22:21 UTC
    Reported by NVD · NVD
  3. 25 Oct 2026, 18:50 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-91637 · GHSA-gj8q-cjmv-6jxc
CVSS
9.9 / 10
EPSS
0.3% chance of exploitation within 30 days
Disclosed
20 Oct 2026, 22:21 UTC
On Zero Radar
before the radar started
Last change
25 Oct 2026, 18:50 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Oracle Essbase flaw lets low-privilege users take over the server · Zero Radar