CVE-2026-58249: SAP NetWeaver and Web Dispatcher DOS Vulnerability

CVE-2026-58249 is a denial of service vulnerability in SAP NetWeaver and SAP Web Dispatcher caused by improper validation in internal protocol components. Attackers can crash affected processes remotely without authentication. This article covers technical details, affected versions, impact assessment, and mitigation strategies.

CVE-2026-58249 Overview

CVE-2026-58249 affects SAP NetWeaver and SAP Web Dispatcher. The flaw stems from improper validation of fields in requests processed by an internal protocol component. An unauthenticated remote attacker can send a crafted request that triggers a memory-handling error, crashing the affected process. The vulnerability is categorized under [CWE-191] Integer Underflow. Successful exploitation impacts availability only. Confidentiality and integrity of the application remain unaffected.

Critical Impact
Unauthenticated remote attackers can crash SAP NetWeaver and SAP Web Dispatcher processes, disrupting business-critical SAP services without any user interaction.

Affected Products

SAP NetWeaver
SAP Web Dispatcher
Internal protocol component shared across the above products

Discovery Timeline

2026-10-13 - CVE-2026-58249 published to NVD
2026-10-15 - Last updated in NVD database

Technical Details for CVE-2026-58249

Vulnerability Analysis

The vulnerability resides in an internal protocol component used by SAP NetWeaver and SAP Web Dispatcher. The component fails to properly validate certain fields in incoming requests. When processed, the malformed input leads to a memory-handling error consistent with [CWE-191] Integer Underflow. The resulting condition causes the affected worker process to terminate, interrupting request handling for connected clients.

Because SAP Web Dispatcher sits in front of SAP application servers as a reverse proxy and load balancer, a process crash directly impacts the availability of downstream SAP applications. Repeated exploitation enables sustained denial-of-service conditions against production ERP, BW, and S/4HANA landscapes.

Root Cause

An integer underflow occurs when the component computes a length or offset value from attacker-controlled fields without proper bounds checking. The underflowed value is then used in a subsequent memory operation, producing an invalid access that crashes the process. SAP has not published implementation specifics in the public advisory.

Attack Vector

Exploitation requires only network reachability to the vulnerable SAP service. No authentication or user interaction is needed. An attacker crafts a single malicious request targeting the internal protocol component. The server processes the request, triggers the memory-handling error, and the process crashes. No code execution or data exposure is possible through this flaw.

No verified proof-of-concept code is publicly available. Refer to SAP Note #3765424 for vendor technical details.

Detection Methods for CVE-2026-58249

Indicators of Compromise

Unexpected termination of SAP Web Dispatcher or NetWeaver work processes with core dumps referencing the internal protocol handler.
Repeated process restarts logged in dev_webdisp, dev_disp, or related SAP trace files.
Spikes in malformed inbound requests to SAP service ports from a limited set of source IPs.

Detection Strategies

Monitor SAP system logs (SM21) and developer traces for abnormal termination events tied to protocol parsing.
Correlate network IDS/IPS alerts on SAP service ports with SAP process restart events.
Baseline normal request patterns to SAP Web Dispatcher and flag protocol-level anomalies.

Monitoring Recommendations

Enable alerting on SAP work process crash counters and ICM restart events.
Forward SAP host and application logs to a centralized SIEM for correlation with network telemetry.
Track availability SLAs of SAP front-end services to detect intermittent outages indicative of DoS attempts.

How to Mitigate CVE-2026-58249

Immediate Actions Required

Apply the SAP security patch referenced in SAP Note #3765424 during the next scheduled maintenance window.
Review SAP October 2026 Security Patch Day advisories at the SAP Security Patch Day portal.
Restrict network exposure of SAP Web Dispatcher and NetWeaver endpoints to trusted networks only.

Patch Information

SAP has released fixes documented in SAP Note #3765424 as part of SAP Security Patch Day. Administrators should authenticate to the SAP Support Portal, download the corresponding patch for the affected SAP kernel or Web Dispatcher version, and apply it following standard SAP change-management procedures. Validate the fix in non-production landscapes before rolling to production.

Workarounds

Place SAP Web Dispatcher behind a filtering reverse proxy or web application firewall configured to drop malformed protocol requests.
Enforce source-IP access control lists on SAP service ports to limit exposure to authorized clients.
Enable automatic process restart and health-check watchdogs to minimize downtime from forced crashes while the patch is being deployed.

bash

# Example: restrict SAP Web Dispatcher ports with iptables to a trusted subnet
iptables -A INPUT -p tcp --dport 44300 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 44300 -j DROP
iptables -A INPUT -p tcp --dport 8100  -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8100  -j DROP