CVE-2025-42934 is a vulnerability identified in the SAP S/4HANA Supplier Invoice component, specifically related to improper neutralization of CRLF (Carriage Return Line Feed) sequences in HTTP headers, categorized under CWE-113. This vulnerability allows an attacker with user-level privileges to inject line feed (LF) characters into application inputs, thereby bypassing the allowlist mechanism that controls the 'Trusted Sites' configuration. By exploiting this flaw, the attacker can insert untrusted or malicious sites into the trusted sites list, potentially influencing how the application handles external content or requests. The vulnerability affects multiple versions of SAP S/4HANA (S4CORE 102 through 109). The CVSS v3.1 base score is 4.3, indicating a medium severity level. The vector string (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N) indicates that the attack can be executed remotely over the network with low attack complexity, requires low privileges (user-level), does not require user interaction, and impacts only the integrity of the application without affecting confidentiality or availability. No known exploits are currently reported in the wild, and no patches have been linked yet. The core technical issue is the failure to properly sanitize or neutralize CRLF characters in HTTP headers, which can lead to HTTP response splitting or header injection scenarios. Although the impact is limited to integrity and does not compromise confidentiality or availability, the ability to manipulate trusted site configurations could facilitate further attacks such as phishing, session hijacking, or cross-site scripting if combined with other vulnerabilities or social engineering techniques.

For European organizations using SAP S/4HANA, particularly those relying on the Supplier Invoice module, this vulnerability poses a moderate risk. The primary impact is on the integrity of the application’s configuration, specifically the trusted sites list. If exploited, attackers could insert malicious sites into the trusted list, potentially enabling further attacks that leverage trust relationships, such as redirecting users to malicious sites or bypassing security controls that rely on trusted site configurations. While confidentiality and availability are not directly impacted, the integrity compromise could lead to reputational damage, compliance issues (especially under GDPR if user data is indirectly affected), and potential financial losses if attackers use this foothold for fraud or further exploitation. Given SAP’s widespread use in European enterprises across sectors like manufacturing, finance, and public administration, the vulnerability could have broad implications if not addressed. However, the requirement for user-level privileges and the absence of user interaction reduce the likelihood of widespread exploitation without insider access or compromised credentials.

To mitigate this vulnerability, European organizations should take the following specific actions: 1) Immediately review and restrict user privileges to ensure that only trusted personnel have access to the Supplier Invoice module, minimizing the risk of exploitation by low-privilege users. 2) Implement strict input validation and sanitization controls on all inputs that influence HTTP headers or trusted site configurations, potentially through custom SAP security configurations or middleware filtering. 3) Monitor and audit changes to the trusted sites list regularly to detect unauthorized modifications promptly. 4) Apply SAP security notes and patches as soon as they become available, even though none are currently linked, maintaining close communication with SAP support channels. 5) Employ network-level controls such as web application firewalls (WAFs) configured to detect and block CRLF injection attempts in HTTP headers. 6) Conduct security awareness training for users with access to SAP modules to recognize and report suspicious activities that could indicate exploitation attempts. 7) Consider implementing additional logging and alerting mechanisms within SAP to capture anomalous configuration changes or injection attempts.