Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate with low-privileged Siebel account
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ExploitAbuse Open UI component flaw
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ImpactRead critical Siebel CRM data
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK
1 technique across 1 tactic: Defense Evasion The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires the attacker to already have an authenticated low-privileged account with logon access to the infrastructure where Siebel CRM End User runs (per PR:L and the description's explicit 'logon to the infrastructure' wording), and the affected Open UI component must be in use on a version in the 17.0-26.9 range. Limiting factors: the attack vector is LOCAL (AV:L) - not exploitable remotely over a network - and valid credentials are mandatory, so purely external, unauthenticated attackers cannot leverage it directly; impact is confined to reading data (no integrity or availability effect). |
| Impact | This is a moderate-severity, confidentiality-only issue (CVSS 3.1 base 5.5) that is unlikely to be a top-tier emergency. The vendor-supplied vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N indicates LOCAL attack vector requiring an already-authenticated low-privileged account (PR:L) with logon to the infrastructure where Siebel CRM End User executes - this is not remotely exploitable from the internet and not an unauthenticated flaw. Impact is limited to confidentiality (C:H, I:N, A:N): an attacker could read critical or all Siebel-accessible data but cannot modify data or disrupt availability. No EPSS score, no CISA KEV listing, and no public POC are present in the provided data, so there is no evidence of active exploitation or weaponization - this appears to be a routine Oracle Critical Patch Update item rather than an urgent threat. A key data conflict exists: the input Tags include 'Authentication Bypass', yet both the description ('low privileged attacker with logon') and the CVSS vector (PR:L) require valid authentication, so the 'Authentication Bypass' label contradicts the authoritative Oracle data and appears mislabeled - verify against the Oracle advisory. CWE is N/A, limiting precise weakness classification. |
| Exploit ScenarioDerived | An attacker who already holds a low-privileged, authenticated Siebel CRM End User account (or local logon to the hosting infrastructure) abuses a flaw in the Open UI component to read Siebel data beyond their authorization level. Because the attack is local and low-complexity (AV:L/AC:L) but requires existing credentials, the most realistic actor is a malicious insider or someone who has already obtained a foothold. No public exploit code is identified at time of analysis. |
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Alert meAnalysisAIv1 – Oct 21, 2026
Confidential data disclosure in Oracle Siebel CRM's End User Open UI affects versions 17.0 through 26.9, allowing a low-privileged user with local logon access to the Siebel infrastructure to read critical data. The CVSS 3.1 score is 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N), so the issue is local, requires valid credentials, and has no integrity or availability impact. No public exploit was identified at time of analysis.
RemediationAI
Patch available per vendor advisory: apply the Oracle Critical Patch Update October 2026 fix for Siebel CRM End User/Open UI; because the input does not give an exact patched build number, confirm the fixed 17.0-26.9 replacement release in Oracle's CPU matrix and validate it before production rollout (https://www.oracle.com/security-alerts/cpuoct2026.html). If patching must wait, restrict interactive and local logon to the Siebel End User infrastructure to trusted, least-privileged operators and review accounts that can reach the Open UI component; this lowers exposure to the AV:L/PR:L precondition but does not remediate the flaw and may disrupt legitimate administrative access. Monitor for unusual read access to Siebel data from low-privileged sessions, and remove unnecessary local accounts.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Oracle Siebel CRM End User is the end-user-facing Siebel client, and Open UI is its browser-based interface layer; CVE-2026-91431 is scoped to that component in releases 17.0 through 26.9. The assessed vector is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N: an attacker needs logon access to the infrastructure hosting the component and a valid low-privileged account, with no user interaction and a scope-unchanged impact limited to confidentiality. No CWE identifier was supplied, so the precise coding weakness is not confirmed; the C:H/I:N/A:N profile is consistent with an information-disclosure or read-boundary failure. Intelligence tags label it 'Authentication Bypass', but the PR:L requirement and the explicit 'logon to the infrastructure' wording mean it should not be treated as an unauthenticated bypass based on available data.
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Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Description requires an authenticated low-privileged local logon (PR:L, AV:L), low complexity, no user interaction, with high confidentiality-only impact and no integrity/availability effect.
Primary rating from Vendor (oracle).
CVSS VectorVendor: oracle
DescriptionCVE.org
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 logon to the infrastructure where Siebel CRM End User executes to compromise Siebel CRM End User. Successful attacks of this vulnerability can result in unauthorized access to critical data or complete access to all Siebel CRM End User accessible data. CVSS 3.1 Base Score 5.5 (Confidentiality impacts). CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N).
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
EUVD-2026-106681
GHSA-hhmr-6jjw-xxgx
NVD
CVE.org
EPSS
Exploit-DB