---
id: "CVE-2026-91644"
kind: "vulnerability"
aliases: ["CVE-2026-91644"]
title: "Oracle Essbase: unauthenticated network attacker can read and alter data"
severity: "critical"
cvss: 9.3
epss: 0.00218
exploited: false
status: "open"
category: "runtime"
products: [{"name": "oracle essbase", "fixed": [], "affected": "= 21.8.3.0.0", "ecosystem": "vendor"}, {"name": "essbase", "fixed": [], "affected": "21.8.3.0.0", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["analytics", "infrastructure", "oracle-essbase", "runtime", "self-hosted"]
not_affected_if: ["managed-hosting", "other-versions"]
published_at: "2026-10-20T22:21:04+00:00"
first_seen_at: "2026-10-23T21:57:27+00:00"
updated_at: "2026-10-24T13:15:55+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91644", "first_seen_at": "2026-10-23T21:57:27+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T22:55:15+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91644", "first_seen_at": "2026-10-24T13:15:55+00:00"}]
---

# Oracle Essbase: unauthenticated network attacker can read and alter data

Oracle Essbase, a multidimensional analytics server, has a flaw in its Security component that lets an unauthenticated attacker reach it over HTTP. A successful attack gives read access to all Essbase data and write, insert and delete access to some of it, and can also affect other products.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:oracle essbase affected = 21.8.3.0.0 fixed ?
- vendor:essbase affected 21.8.3.0.0 fixed ?

## How to check

Check the Essbase version. 21.8.3.0.0 is the only affected version Oracle lists. Then check whether the October 2026 CPU patch is installed (OPatch lsinventory or the Essbase release info). Exposure is worst if Essbase's HTTP port is reachable from untrusted networks.

## Fix

Apply the Oracle Essbase patch from the October 2026 Critical Patch Update, found via the Database entry in the CPU patch availability document on My Oracle Support. The fixed release name is not published publicly: unknown until read on MOS.

## Timeline

- 2026-10-23T21:57:27+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91644
- 2026-10-23T22:55:15+00:00 analyst — Oracle October 2026 CPU (cpuoct2026) lists Essbase 21.8.3.0.0 as affected, CVSS 9.3 (AV:N/PR:N/S:C/C:H/I:L), fix delivered as CPU patch under the Database patch availability doc on My Oracle Support (login needed). Exact patch number/fixed release not public; not guessed. No exploitation reported, no PoC, no X posts. Armis page mentions T3/IIOP port mitigation, which does not fit an HTTP flaw; ignored.
- 2026-10-24T13:15:55+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91644

## Documents

- [advisory] Oracle Critical Patch Update Advisory - October 2026 https://www.oracle.com/security-alerts/cpuoct2026.html
- [advisory] Text Form of Oracle CPU October 2026 Risk Matrices https://www.oracle.com/security-alerts/cpuoct2026verbose.html

## From the sources

Vulnerability in Oracle Essbase (component: Security).   The supported version that is affected is 21.8.3.0.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise Oracle Essbase.  While the vulnerability is in Oracle Essbase, attacks may significantly impact additional products (scope change).  Successful attacks of this vulnerability can result in  unauthorized access to critical data or complete access to all Oracle Essbase accessible data as well as  unauthorized update, insert or delete access to some of Oracle Essbase accessible data. CVSS 3.1 Base Score 9.3 (Confidentiality and Integrity impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N).

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_