---
id: "CVE-2026-91421"
kind: "vulnerability"
aliases: ["CVE-2026-91421"]
title: "Oracle Siebel CRM Deployment: unauthenticated HTTP request can hang or crash server"
severity: "medium"
cvss: 5.9
epss: 0.00367
exploited: false
status: "open"
category: "vendor"
products: []
ecosystems: []
tags: ["oracle", "self-hosted", "siebel-crm", "vendor"]
not_affected_if: ["unaffected-version"]
published_at: "2026-10-20T22:20:45+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-2026-91421", "first_seen_at": "2026-10-23T21:57:26+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91421", "first_seen_at": "2026-10-25T12:38:52+00:00"}]
---

# Oracle Siebel CRM Deployment: unauthenticated HTTP request can hang or crash server

Oracle Siebel CRM Deployment, Server Infrastructure component, versions 17.0 through 26.9, has a flaw reachable over HTTP without credentials. A remote attacker can repeatedly hang or crash the service, causing denial of service.

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

## How to check

- Identify Siebel CRM Deployment installs and their version: unknown
- Confirm whether the Server Infrastructure component is exposed over HTTP to the network: unknown

## Fix

- Apply the Oracle Critical Patch Update fix for Siebel CRM 17.0 to 26.9: unknown patch level in sources

## Timeline

- 2026-10-23T21:57:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91421
- 2026-10-25T12:38:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91421

## From the sources

Vulnerability in the Siebel CRM Deployment product of Oracle Siebel CRM (component: Server Infrastructure).  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 Deployment.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Siebel CRM Deployment. CVSS 3.1 Base Score 5.9 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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_