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CriticalVulnerabilityCVE-2026-91655updated 25 Oct 2026, 18:50 UTC

Oracle Essbase flaw lets low-privilege users take over data over HTTP

A flaw in Oracle Essbase, a business data analysis tool, lets someone with a basic user account reach data they should not see or change. The attack can be carried out over the network, so anyone who can reach the server could try it.

Official, 2 sources
SeverityCriticalCVSS 9.1 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 userHolds a basic account or gains one
  2. 2HTTP requestSent to the Essbase server over the network
  3. 3Security flawFlaw in Essbase lets request bypass controls
  4. 4Data accessedCritical data read, changed, or deleted
  5. ResultAttacker reaches data beyond their rights

What happened

Oracle Essbase version 21.8.3.0.0 has a critical Security component vulnerability exploitable remotely over HTTP by a low-privileged attacker, with a scope change that can impact other products. The GitHub advisory adds no further technical detail.

Why it is dangerous: Successful attacks can expose critical data or all Essbase-accessible data, allow unauthorized changes or deletions, and cause partial denial of service. Organizations running Essbase with HTTP access and any user accounts are at risk.

Are you affected?

You are affected if you run Oracle Essbase 21.8.3.0.0 and users or attackers with low-privilege accounts can reach it over HTTP.

Oracle Essbase 21.8.3.0.0

What to do

  1. Check whether you run Oracle Essbase 21.8.3.0.0
  2. Check Oracle's security advisory for a patched version and apply it
  3. Restrict HTTP access to Essbase to trusted networks until patched
  4. Review accounts with Essbase access and remove unneeded ones

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-2026-91655 · GHSA-6mw7-mcpr-3q6v
CVSS
9.1 / 10
EPSS
0.2% 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 data over HTTP · Zero Radar