---
id: "CVE-2026-91388"
kind: "vulnerability"
aliases: ["CVE-2026-91388"]
title: "Oracle Siebel CRM End User: Open UI flaw allows data read and write"
severity: "medium"
cvss: 4.7
epss: 0.00149
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-2026-91388", "first_seen_at": "2026-10-23T21:57:26+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91388", "first_seen_at": "2026-10-25T12:38:52+00:00"}]
---

# Oracle Siebel CRM End User: Open UI flaw allows data read and write

Oracle Siebel CRM End User has a flaw in its Open UI component that lets an unauthenticated attacker reach the application over HTTP. A successful attack, which needs a user to interact with a crafted request, can read and modify a subset of the CRM data the user can access.

_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 to 26.9 in the Oracle advisory
- unknown

## Fix

- Apply the Oracle Critical Patch Update fix for Siebel CRM, per the Oracle advisory
- unknown

## Timeline

- 2026-10-23T21:57:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91388
- 2026-10-25T12:38:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91388

## 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. Difficult to exploit vulnerability allows unauthenticated 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 4.7 (Confidentiality and Integrity impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/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_