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CriticalVulnerabilityCVE-2026-91665updated 25 Oct 2026, 18:50 UTC

Oracle Essbase can be fully taken over by unauthenticated network attackers

Oracle Essbase is business analytics software. A flaw lets someone on the network take control of it without logging in, which could expose or change the business data it holds.

Official, 2 sources
SeverityCriticalCVSS 9.8 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. 1AttackerRemote, no login needed
  2. 2TCP connectionReaches Essbase over the network
  3. 3Security flawUnauthenticated access is granted
  4. 4Essbase serverAttacker gains control
  5. ResultAttacker takes over Essbase

What happened

An easily exploitable flaw in the Security component of Oracle Essbase allows an unauthenticated attacker with TCP network access to fully compromise the product.

Why it is dangerous: A successful attack can lead to full takeover of Essbase, affecting confidentiality, integrity and availability. Organizations running exposed Essbase servers are at risk.

Are you affected?

You are affected if you run Oracle Essbase 21.8.3.0.0 and its network port is reachable by untrusted parties.

Oracle Essbase 21.8.3.0.0 (supported version)

What to do

  1. Check whether your Essbase server runs version 21.8.3.0.0 and confirm the version with Oracle's advisory
  2. Restrict network access to Essbase so only trusted hosts can reach it over TCP
  3. Apply the Oracle Critical Patch Update or vendor fix as soon as it is available for your version

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-2026-91665 · GHSA-6w29-5x85-gw26
CVSS
9.8 / 10
EPSS
0.5% 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 fully taken over by unauthenticated network attackers · Zero Radar