CVE-2026-101399 in Siebel Apps
Summary
by MITRE • 10/21/2026
Vulnerability in the Siebel Apps - Marketing product of Oracle Siebel CRM (component: Marketing). Supported versions that are affected are 17.0-26.9. Easily exploitable vulnerability allows unauthenticated attacker with network access via SMTP to compromise Siebel Apps - Marketing. Successful attacks of this vulnerability can result in unauthorized ability to cause a partial denial of service (partial DOS) of Siebel Apps - Marketing. CVSS 3.1 Base Score 5.3 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).
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Analysis
by VulDB Data Team • 10/21/2026
The identified vulnerability resides within the Marketing component of Oracle Siebel CRM, specifically affecting supported versions ranging from 17.0 through 26.9. This security flaw is classified as a critical infrastructure weakness that permits unauthenticated attackers to exploit the system via the Simple Mail Transfer Protocol (SMTP). The presence of this vulnerability indicates a significant deficiency in how the application handles incoming mail traffic or processes specific SMTP commands, allowing an external actor with network access to interact directly with the service without requiring valid credentials. This lack of authentication requirement at the protocol level represents a fundamental failure in input validation and session management for the affected module.
From a technical perspective, the exploitation mechanism leverages the inherent trust placed in standard email protocols by many enterprise applications that integrate mail functionality. An attacker can craft specific SMTP requests or payloads designed to trigger resource exhaustion conditions within the Siebel Marketing engine. The vulnerability does not result in data exfiltration or unauthorized modification of business logic but rather targets the availability of the service. By sending malformed or excessively demanding commands, an adversary can cause the application processes associated with marketing activities to become unresponsive or crash, leading to a partial denial of service. This impact is particularly damaging for organizations relying on automated email campaigns and customer communication workflows managed through Siebel Apps.
The operational impact of this vulnerability centers on availability disruption rather than confidentiality or integrity breaches. A successful exploitation results in the degradation or temporary suspension of marketing-related services within the CRM environment. For businesses that depend heavily on real-time campaign management, lead nurturing, and automated email dispatches via Oracle Siebel, such disruptions can halt critical business operations and damage customer relationships. The CVSS 3.1 base score of 5.3 reflects a medium severity rating driven primarily by availability impacts. The vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) confirms that the attack is network-based, requires low complexity, demands no user interaction or privileges, and results in only local impact on availability without affecting other system components' confidentiality or integrity.
In terms of industry standard classifications, this vulnerability aligns with CWE-400, which denotes uncontrolled resource consumption leading to denial of service conditions. It also maps closely to MITRE ATT&CK techniques related to Resource Hijacking and Service Disruption, where adversaries aim to degrade the performance or availability of targeted systems rather than stealing data. Understanding these mappings is crucial for security teams aiming to detect similar patterns in network traffic logs and endpoint monitoring tools. The lack of authentication requirements further highlights a gap in access control mechanisms that should be addressed through stricter protocol handling policies within the application layer.
Mitigation strategies must focus on immediate remediation and defensive hardening. Oracle has likely released patches or updates addressing this specific flaw, making patch management the primary defense vector for administrators managing Siebel CRM environments. Organizations running affected versions between 17.0 and 26.9 should prioritize applying these security updates to restore full functionality and close the exploitation path. In addition to patching, network-level controls such as rate limiting on SMTP connections can help mitigate potential abuse by restricting the volume of requests a single source can send in a given timeframe. Implementing strict input validation for all mail-related inputs within the application codebase is also essential to prevent similar vulnerabilities from being introduced or exploited in other modules. Regular security assessments and penetration testing focused on email integration points will further ensure that such availability risks are identified and resolved before they impact business continuity.