---
id: "CVE-2026-91647"
kind: "vulnerability"
aliases: ["CVE-2026-91647"]
title: "Oracle Essbase: unauthenticated network flaw allows full takeover of server"
severity: "high"
cvss: 8.1
epss: 0.00255
exploited: false
status: "open"
category: "vendor"
products: [{"name": "oracle essbase", "fixed": [], "affected": "= 21.8.3.0.0", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["on-prem-analytics", "oracle-essbase", "self-hosted", "vendor"]
not_affected_if: ["isolated-network", "other-version"]
published_at: "2026-10-20T22:21:04+00:00"
first_seen_at: "2026-10-23T21:57:27+00:00"
updated_at: "2026-10-25T03:06:00+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91647", "first_seen_at": "2026-10-23T21:57:27+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91647", "first_seen_at": "2026-10-24T13:15:55+00:00"}]
---

# Oracle Essbase: unauthenticated network flaw allows full takeover of server

Oracle Essbase 21.8.3.0.0 has a Security component flaw that an unauthenticated attacker can reach over TCP. Successful exploitation can lead to full takeover of the Essbase server, with high confidentiality, integrity and availability impact.

_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 ?

## How to check

- Check the installed Essbase version against `21.8.3.0.0`
- Confirm whether Essbase is reachable from untrusted networks, since the sources say the attack is over TCP
- Fix version: unknown

## Fix

- Apply the Oracle Critical Patch Update that addresses CVE-2026-91647 for Essbase (patch identifier: unknown)
- Restrict network access to Essbase ports until patched

## Timeline

- 2026-10-23T21:57:27+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91647
- 2026-10-24T13:15:55+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91647

## From the sources

Vulnerability in Oracle Essbase (component: Security).   The supported version that is affected is 21.8.3.0.0. Difficult to exploit vulnerability allows unauthenticated attacker with network access via TCP to compromise Oracle Essbase.  Successful attacks of this vulnerability can result in takeover of Oracle Essbase. CVSS 3.1 Base Score 8.1 (Confidentiality, Integrity and Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H).

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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_