CVE-2025-42934: SAP S/4HANA Auth Bypass Vulnerability

CVE-2025-42934 Overview

CVE-2025-42934 is a Carriage Return Line Feed (CRLF) Injection vulnerability in the SAP S/4HANA Supplier Invoice component. An authenticated attacker with user-level privileges can inject line feed (LF) characters into application inputs to bypass allowlist validation. Successful exploitation lets the attacker insert untrusted sites into the Trusted Sites configuration.

The flaw is tracked under CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers. The vulnerability affects application integrity only, with no direct impact on confidentiality or availability.

Critical Impact
Authenticated attackers can bypass allowlist controls and register attacker-controlled domains as trusted, enabling downstream trust-relationship abuse against SAP S/4HANA users.

Affected Products

SAP S/4HANA Supplier Invoice component
Refer to SAP Note #3616863 for the authoritative list of affected releases and support package levels
Full vendor guidance is published on the SAP Security Patch Day Announcement page

Discovery Timeline

2025-08-12 - CVE-2025-42934 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-42934

Vulnerability Analysis

The SAP S/4HANA Supplier Invoice module accepts user-controlled input that flows into the Trusted Sites configuration without proper neutralization of line-ending characters. Attackers craft input containing embedded line feed (LF) characters. When the application processes the input, the injected LF sequence splits the value across configuration entries.

This structural manipulation lets an attacker append an arbitrary site entry that bypasses the allowlist enforcement logic. The allowlist assumes each entry corresponds to a validated site, but CRLF-injected payloads break that assumption. The result is that attacker-chosen origins are treated as trusted by the SAP application.

Exploitation requires an authenticated session with standard user privileges. No user interaction from a victim is required to modify the configuration, and the attack is conducted over the network against the SAP application interface.

Root Cause

The root cause is missing sanitization of CRLF characters in inputs that populate the Trusted Sites list. The application does not strip or reject \r (CR) and \n (LF) byte sequences before writing values into a structured configuration store, permitting record injection as described in CWE-113.

Attack Vector

An authenticated user submits input to a vulnerable Supplier Invoice endpoint that contains an embedded LF character followed by an attacker-controlled hostname. The server processes the payload, and the injected line becomes an additional entry in the trusted sites configuration. Subsequent trust checks against the attacker-controlled site succeed, enabling integrity abuse of features gated by that allowlist.

No verified public proof-of-concept is available. Refer to SAP Note #3616863 for vendor-supplied technical details.

Detection Methods for CVE-2025-42934

Indicators of Compromise

Unexpected entries in the SAP S/4HANA Trusted Sites configuration, particularly domains not owned or approved by the organization
Application audit log entries showing modifications to trusted sites originating from non-administrative user accounts
HTTP request bodies or parameters containing %0A, %0D%0A, or raw LF/CR bytes directed at Supplier Invoice endpoints

Detection Strategies

Enable and review SAP Security Audit Log (SAL) events for configuration changes to trusted sites and correlate with the initiating user role
Deploy web application firewall (WAF) or reverse-proxy rules that flag CRLF byte sequences in request parameters targeting SAP endpoints
Periodically diff the Trusted Sites allowlist against an approved baseline to identify unauthorized additions

Monitoring Recommendations

Forward SAP application and audit logs to a centralized SIEM for cross-session correlation of configuration changes
Alert on non-administrative accounts performing writes to trust-sensitive configuration objects
Monitor egress traffic to newly added trusted sites for signs of data exfiltration or phishing redirection

How to Mitigate CVE-2025-42934

Immediate Actions Required

Apply the patch documented in SAP Note #3616863 to affected SAP S/4HANA systems
Audit the current Trusted Sites configuration and remove any entries not explicitly approved by change management
Restrict Supplier Invoice module authorization objects to users with a documented business need

Patch Information

SAP addressed CVE-2025-42934 through the security correction distributed on SAP Security Patch Day. Administrators should review SAP Note #3616863 for the applicable support package or note implementation, and consult the SAP Security Patch Day Announcement for cross-referenced fixes.

Workarounds

Enforce strict input validation at a reverse proxy or WAF that rejects requests containing CR (\r) or LF (\n) bytes in parameters that feed configuration APIs
Reduce the blast radius by tightening role-based access so only trusted administrators can modify trust-related configuration objects
Increase audit-log retention and alerting on Trusted Sites modifications until the patch is deployed across all systems

bash

# Example WAF rule concept - reject CRLF in SAP request parameters
# ModSecurity-style pattern (adapt to your WAF syntax)
SecRule ARGS "@rx (?:%0[aAdD]|\r|\n)" \
    "id:1004293,phase:2,deny,status:400,\
     msg:'CRLF injection attempt against SAP endpoint (CVE-2025-42934)'"