---
id: "CVE-2026-91637"
kind: "vulnerability"
aliases: ["CVE-2026-91637"]
title: "Oracle Essbase: low-privilege network attacker can take over server"
severity: "critical"
cvss: 9.9
epss: 0.00286
exploited: false
status: "open"
category: "other"
products: [{"name": "oracle essbase", "fixed": [], "affected": "= 21.8.3.0.0", "ecosystem": "vendor"}, {"name": "oracle essbase", "fixed": [], "affected": "21.8.3.0.0", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["cpu-october-2026", "oracle", "oracle-essbase", "other", "self-hosted", "vendor"]
not_affected_if: []
published_at: "2026-10-20T22:21:03+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-2026-91637", "first_seen_at": "2026-10-23T21:57:27+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T22:55:13+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91637", "first_seen_at": "2026-10-24T13:15:55+00:00"}]
---

# Oracle Essbase: low-privilege network attacker can take over server

Oracle Essbase 21.8.3.0.0 has a flaw in its Security component. A low-privilege account can reach it over HTTP and take over the server, with impact on other products (CVSS 9.9). Oracle fixed it in the October 2026 CPU. Oracle's public page names no fixed version.

_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:oracle essbase affected 21.8.3.0.0 fixed ?

## How to check

Find your Essbase version. Oracle lists only 21.8.3.0.0 as affected. Then check whether the October 2026 CPU Essbase patch is applied, using the 'Database' patch availability document on My Oracle Support. Any Essbase HTTP endpoint reachable by a low-privilege account is exposed.

## Fix

Apply the Essbase patch from Oracle's October 2026 Critical Patch Update (see the Database patch availability document on My Oracle Support). The exact fixed version or patch number is unknown; reading that MOS document would settle it. Until then, limit network access to Essbase HTTP and review low-privilege accounts.

## Timeline

- 2026-10-23T21:57:27+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91637
- 2026-10-23T22:55:13+00:00 analyst — Oracle CPU Oct 2026 lists CVE-2026-91637 (Essbase, Security, HTTP, CVSS 9.9, PR:L, scope changed, affects 21.8.3.0.0). The advisory gives no fixed version; the patch is in the 'Database' patch availability document on My Oracle Support (support contract needed), which I could not read. No exploitation or PoC found, and no X posts.
- 2026-10-24T13:15:55+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91637

## Documents

- [advisory] Oracle Critical Patch Update Advisory - October 2026 https://www.oracle.com/security-alerts/cpuoct2026.html
- [describes] CVE Record: CVE-2026-91637 https://www.cve.org/CVERecord?id=CVE-2026-91637

## 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 low privileged 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 takeover of Oracle Essbase. CVSS 3.1 Base Score 9.9 (Confidentiality, Integrity and Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H).

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