CVE-2025-42873 is a vulnerability identified in the SAPUI5 framework, specifically within the Markdown-it component used for rendering markdown content. The root cause is the use of outdated third-party libraries that contain known security flaws. When the Markdown-it parser processes specially crafted malformed input, it enters an infinite loop due to improper termination conditions. This infinite loop causes excessive CPU consumption, leading to Denial of Service (DoS) by making the system unresponsive and blocking the processing thread responsible for handling requests. The vulnerability affects SAP_UI versions 755, 756, 757, and 758. The attack vector is network-based, requiring no privileges or user interaction, but the complexity is high due to the need to craft specific malformed markdown input. The vulnerability impacts system availability but does not affect confidentiality or integrity of data. No patches were available at the time of disclosure, and no known exploits have been observed in the wild. The CVSS 3.1 base score is 5.9, reflecting a medium severity rating. This vulnerability is classified under CWE-405 (Asymmetric Resource Consumption), highlighting that the resource exhaustion arises from malformed input causing disproportionate processing overhead. Organizations using SAPUI5 for web applications or enterprise portals should be aware of this risk, as it can disrupt service availability and degrade user experience.

For European organizations, the primary impact of CVE-2025-42873 is on system availability. SAPUI5 is widely used in enterprise environments across Europe for building business-critical web applications and portals. An attacker exploiting this vulnerability can cause high CPU usage leading to system unresponsiveness or downtime, potentially disrupting business operations, customer-facing services, and internal workflows. This can result in operational delays, financial losses, and reputational damage. Since the vulnerability does not affect confidentiality or integrity, data breaches are unlikely; however, the denial of service can indirectly affect compliance with service-level agreements (SLAs) and regulatory requirements for uptime and availability. Organizations in sectors such as finance, manufacturing, public administration, and utilities that rely heavily on SAPUI5-based applications are particularly vulnerable. The lack of available patches at disclosure increases the window of exposure, emphasizing the need for proactive mitigation. Additionally, the medium CVSS score suggests that while exploitation is not trivial, motivated attackers with network access could leverage this vulnerability to disrupt services.

1. Monitor system and application logs for unusual CPU spikes or performance degradation in SAPUI5 applications, especially those rendering markdown content. 2. Restrict network access to SAPUI5 interfaces to trusted users and IP ranges using firewalls or network segmentation to reduce exposure. 3. Implement input validation and sanitization at the application layer to detect and block malformed markdown input before it reaches the Markdown-it parser. 4. Deploy rate limiting or request throttling on endpoints processing markdown content to mitigate potential DoS attempts. 5. Engage with SAP support channels to obtain and apply official patches or updates as soon as they become available. 6. Consider temporary workarounds such as disabling markdown rendering features if feasible until patches are applied. 7. Conduct regular security assessments and penetration testing focusing on input handling in SAPUI5 applications. 8. Educate development and operations teams about this vulnerability to ensure rapid detection and response to potential exploitation attempts.