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CriticalVulnerabilityCVE-2026-91638updated 25 Oct 2026, 18:50 UTC

Oracle Essbase can be taken over by a low-privileged user over HTTP

Someone with a basic login to Oracle Essbase, reachable over the network, could take control of the whole server. Attacks could also spread to 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 attackerHas any valid user account
  2. 2HTTP requestReaches Essbase over the network
  3. 3Security component flawFlaw lets attacker escalate control
  4. 4Essbase taken overFull control of the server
  5. ResultAttacker takes over Essbase and may spread further

What happened

A security flaw in the Security component of Oracle Essbase 21.8.3.0.0 lets a low-privileged attacker with network access over HTTP fully compromise the product, with scope change to other components.

Why it is dangerous: A successful attack can fully take over Oracle Essbase and may affect other systems connected to it, impacting confidentiality, integrity and availability. Organizations running Essbase on the network with user accounts are at risk.

Are you affected?

You are affected if you run Oracle Essbase version 21.8.3.0.0 and it is reachable over the network via HTTP.

Oracle Essbase 21.8.3.0.0

What to do

  1. Check whether Oracle Essbase 21.8.3.0.0 is in use, especially if it is reachable from the network
  2. Restrict network access to Essbase HTTP services to trusted users and systems only
  3. Watch Oracle's security advisories and apply the vendor patch as soon as it is released

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-2026-91638 · GHSA-3q4w-6qv6-vpj6
CVSS
9.9 / 10
EPSS
0.4% 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 can be taken over by a low-privileged user over HTTP · Zero Radar