---
id: "CVE-2026-91389"
kind: "vulnerability"
aliases: ["CVE-2026-91389"]
title: "Oracle Siebel CRM End User: Open UI flaw lets low-privilege users change data"
severity: "medium"
cvss: 5.4
epss: 0.00195
exploited: false
status: "open"
category: "vendor"
products: []
ecosystems: []
tags: ["oracle", "self-hosted", "siebel-crm", "vendor"]
not_affected_if: ["unsupported-version"]
published_at: "2026-10-20T22:20:42+00:00"
first_seen_at: "2026-10-23T21:57:26+00:00"
updated_at: "2026-10-25T12:38:52+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91389", "first_seen_at": "2026-10-23T21:57:26+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91389", "first_seen_at": "2026-10-25T12:38:52+00:00"}]
---

# Oracle Siebel CRM End User: Open UI flaw lets low-privilege users change data

Oracle Siebel CRM End User has a flaw in its Open UI component that lets an attacker with a low-privilege account over HTTP read and modify some data the application can access. Exploitation needs a victim to take an action, and the impact can extend beyond Siebel itself.

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

## How to check

- Check the installed Siebel CRM version against the affected range 17.0-26.9 in the Siebel administration console or release notes
- unknown

## Fix

- Apply the Oracle Siebel CRM Critical Patch Update that covers Open UI for versions 17.0-26.9
- unknown

## Timeline

- 2026-10-23T21:57:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91389
- 2026-10-25T12:38:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91389

## From the sources

Vulnerability in the Siebel CRM End User product of Oracle Siebel CRM (component: Open UI).  Supported versions that are affected are 17.0-26.9. Easily exploitable vulnerability allows low privileged attacker with network access via HTTP to compromise Siebel CRM End User.  Successful attacks require human interaction from a person other than the attacker and while the vulnerability is in Siebel CRM End User, attacks may significantly impact additional products (scope change). Successful attacks of this vulnerability can result in  unauthorized update, insert or delete access to some of Siebel CRM End User accessible data as well as  unauthorized read access to a subset of Siebel CRM End User accessible data. CVSS 3.1 Base Score 5.4 (Confidentiality and Integrity impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N).

---

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