CVE-2026-58249

Executive Summary

CVE-2026-58249 is an unauthenticated availability-impacting vulnerability affecting SAP NetWeaver and SAP Web Dispatcher. The flaw resides in an internal protocol component that fails to properly validate certain request fields, allowing a remote attacker to trigger a memory-handling error (CWE-191, integer underflow leading to improper memory handling) that crashes the affected process. Internet-exposed SAP NetWeaver application servers and Web Dispatcher instances are at risk of denial-of-service, with no impact to confidentiality or integrity.

Technical Analysis

The vulnerability is classified under CWE-191 (Integer Underflow). Per the NVD description, SAP NetWeaver and SAP Web Dispatcher "do not properly validate certain fields in specially crafted requests handled by an internal protocol component." When a malicious request contains malformed field values, the internal protocol handler processes them without adequate boundary validation. This improper validation leads to a memory-handling error, specifically an integer underflow condition, which subsequently causes the affected process to crash.

The attack surface is the internal protocol component's request-handling path. This component is reachable from the network without authentication (AV:N, PR:N), meaning no credentials or prior access are required. The specific protocol, request structure, field names, and code paths are not disclosed in the available NVD description, and no CNA title was provided. Therefore, code-level specifics (function names, parameter identifiers, memory allocation routines) cannot be reliably stated and are not fabricated here.

Key characteristics:

• Root cause class: Integer underflow (CWE-191) resulting in improper memory handling.
• Impact type: Availability only (C:N/I:N/A:H). The crash terminates the affected process; no data disclosure or modification is described.
• Authentication requirement: None — unauthenticated attacker.
• Attack complexity: Low (AC:L), no user interaction (UI:N).
• Affected components: SAP NetWeaver (application server stack) and SAP Web Dispatcher (the reverse-proxy/load-balancing component fronting SAP systems).

Because the Web Dispatcher is frequently placed at the network edge to route traffic to back-end NetWeaver application servers, a crash in this component can disrupt access to multiple downstream SAP applications simultaneously, amplifying the availability impact beyond a single process.

Exploitation Scenarios

No public PoC, exploit code, or Nuclei template exists for this CVE. The following attack chain is inferred strictly from the vulnerability class and the NVD description; no implementation-specific details are invented.

1. Reconnaissance / target identification. An attacker identifies internet-exposed SAP NetWeaver application servers or SAP Web Dispatcher instances. These are commonly enumerated via HTTP/HTTPS service banners, SAP-specific titles, and Shodan queries. The attacker needs only network reachability to the relevant listener; no credentials are required.

2. Triggering the flaw class. The attacker crafts a request directed at the internal protocol component. The crafted request contains malformed values in "certain fields" that the component does not properly validate. Based on the CWE-191 classification, the malformed field causes an integer underflow during memory handling (e.g., a length or size computation that wraps below zero), which the component fails to detect or reject.

3. Payload / execution method. At the vulnerability-class level, the attacker sends the crafted request to the affected listener. The improper validation allows the underflow condition to propagate into a memory-handling operation, producing a fault. No code execution, injection primitive, or authentication bypass is described — the mechanism terminates in a process crash rather than arbitrary code execution.

4. Post-exploitation impact. The affected process crashes, causing a denial of service for the targeted component. In the case of SAP Web Dispatcher, this can render downstream NetWeaver applications unreachable. Repeated requests can sustain the outage. Confidentiality and integrity remain unaffected per the CVSS vector.

Note: The exact request format, protocol framing, and field identifiers are not available in the provided intelligence and are deliberately not fabricated.

Impact Assessment

The CVSS 3.1 base score is 7.5 (High), with vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Subscore interpretation:

• AV:N (Network): Exploitable remotely across a network boundary — internet-facing exposure is sufficient.
• AC:L (Low): No special conditions or race windows are required; a crafted request reliably triggers the flaw.
• PR:N (None): No authentication — the attacker does not need valid credentials.
• UI:N (None): No victim interaction required.
• S:U (Unchanged): Impact is confined to the vulnerable component.
• C:N / I:N: No confidentiality or integrity impact.
• A:H (High): A successful exploit fully crashes the affected process, producing a complete loss of availability for that component.

Business impact: SAP NetWeaver underpins core ERP, CRM, SCM, and business warehouse workloads for many enterprises. SAP Web Dispatcher is often the single ingress point for SAP traffic. A crash of either component can halt business-critical transactions, block user access, and cascade to dependent systems. Because exploitation is unauthenticated and low-complexity, a single low-skilled attacker can cause significant operational disruption. Blast radius is highest for organizations that expose Web Dispatcher or NetWeaver directly to untrusted networks. The EPSS score is not yet available from FIRST.org and no exploitation-in-the-wild evidence exists at the time of writing. CVE is not listed in CISA KEV. No patch is available from any tracked source as of this report.

Detection Guidance

Detection should focus on (a) crash/abnormal-termination telemetry from SAP processes, (b) malformed or anomalous requests hitting NetWeaver/Web Dispatcher listeners, and (c) request-rate anomalies consistent with repeated DoS attempts. Because no public exploit signatures exist, the rules below target the vulnerability class (malformed request bursts correlated with process crashes) rather than a known payload.

Sigma Rule

title: SAP NetWeaver / Web Dispatcher Process Crash - Potential CVE-2026-58249 DoS
id: 8f2c1a44-7b91-4e0a-9c3d-58249aabbcc1
status: experimental
description: Detects abnormal termination or crash of SAP NetWeaver / Web Dispatcher processes that may indicate exploitation of an integer underflow memory-handling flaw (CVE-2026-58249).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-58249
author: valtersit.com
date: 2026/01/01
tags:
  - attack.impact
  - attack.t1499
logsource:
  category: application
  product: sap
detection:
  selection_process:
    Image|endswith:
      - '\sapstartsrv.exe'
      - '\disp+work.exe'
      - '\sapwebdisp.exe'
      - '\sapwebdisp'
  selection_event:
    EventID:
      - 1000
      - 1001
    Provider_Name: 'Application Error'
  selection_keywords:
    - 'sapwebdisp'
    - 'disp+work'
    - 'NetWeaver'
  condition: (selection_process and selection_event) or (selection_keywords and selection_event)
falsepositives:
  - Legitimate maintenance restarts
  - Unrelated OS-level faults
level: high

YARA Rule

rule CVE_2026_58249_SAP_Malformed_Request_Marker
{
    meta:
        description = "Detects strings associated with malformed request handling in SAP NetWeaver / Web Dispatcher crash dumps or logs (CVE-2026-58249). Generic class-level match, not a known payload."
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-58249"
        date = "2026-01-01"
        severity = "high"

    strings:
        $sap1 = "sapwebdisp" ascii nocase
        $sap2 = "disp+work" ascii nocase
        $sap3 = "NetWeaver" ascii nocase
        $err1 = "integer underflow" ascii nocase
        $err2 = "memory" ascii nocase
        $crash = "coredump" ascii nocase

    condition:
        filesize < 50MB and
        (2 of ($sap1, $sap2, $sap3)) and
        ($err1 or $err2 or $crash)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-58249 SAP NetWeaver/Web Dispatcher Suspicious Malformed Request Burst"; flow:to_server,established; http.header_names; content:"User-Agent"; threshold:type both, track by_src, count 20, seconds 10; metadata:created_at 2026_01_01, cve CVE-2026-58249; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-58249; classtype:attempted-dos; sid:5824901; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=10s
  [ network where network.protocol == "http" and destination.port in (80, 443, 8000, 8001, 50000) and url.path != null ]
  [ process where event.action == "process-crashed" and process.name in ("sapwebdisp", "disp+work", "sapstartsrv") ]

Splunk SPL Query

index=sap OR index=os_win
(sourcetype="sap:webdispatcher" OR sourcetype="WinEventLog:Application")
| search ("sapwebdisp" OR "disp+work" OR "NetWeaver" OR ("Application Error" AND ("sapwebdisp" OR "disp+work")))
| where (match(_raw, "(?i)crash") OR match(_raw, "(?i)faulting") OR match(_raw, "(?i)terminated"))
| stats count min(_time) as firstTime max(_time) as lastTime by host, source, dest
| where count >= 3
| convert ctime(firstTime) ctime(lastTime)

Wazuh OSSEC Rule

<group name="sap,cve-2026-58249,">
  <rule id="582491" level="12">
    <decoded_as>sap</decoded_as>
    <match>sapwebdisp|disp\+work|NetWeaver</match>
    <regex>crash|faulting|terminated|underflow</regex>
    <description>CVE-2026-58249 - Potential SAP NetWeaver/Web Dispatcher crash from malformed request</description>
    <mitre>
      <id>T1499</id>
    </mitre>
    <group>application_crash,denial_of_service,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate mitigations

   • Restrict network exposure of SAP Web Dispatcher and NetWeaver listeners to trusted source IP ranges only; place them behind a WAF/ACL. This is the single most effective control given the network-based, unauthenticated nature of the flaw.
   • Enable process auto-restart / high-availability supervision for SAP Web Dispatcher and application server work processes to reduce outage duration from crashes.
   • Enable and centralize crash/abnormal-termination logging and alert on burst patterns (see Detection Guidance).
   • Minimize use of any shared front-end Web Dispatcher serving multiple back-end NetWeaver systems until patched, to limit blast radius.

2. Patch/upgrade steps

   • No vendor patch is currently available from tracked sources; monitor SAP Security Notes and the SAP Support Portal for an updated note addressing CVE-2026-58249.
   • When an official SAP patch/Security Note is released, apply it to all Web Dispatcher and NetWeaver instances, prioritizing internet-facing systems.
   • Validate patch level against the SAP note after maintenance.

3. Long-term hardening

   • Adopt network segmentation so SAP protocol components are not reachable from untrusted networks.
   • Enforce input size/range validation at fronting proxies and WAFs for protocol-level fields where feasible.
   • Maintain an inventory of SAP listener exposure and routinely re-scan for internet-facing SAP components.
   • Subscribe to SAP Security Notes and CISA advisories for timely patch intelligence; track EPSS/KEV status for this CVE as it evolves.

References

• NVD — CVE-2026-58249: https://nvd.nist.gov/vuln/detail/CVE-2026-58249
• SAP Security Notes (vendor advisory portal): https://support.sap.com/en/my-support/knowledge-base/security-notes-news.html
• CWE-191 (Integer Underflow): https://cwe.mitre.org/data/definitions/191.html
• FIRST EPSS (score not yet available at time of writing): https://www.first.org/epss/
• CISA Known Exploited Vulnerabilities Catalog (CVE not listed): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

No known threat actor campaigns or exploit-in-the-wild evidence exist for CVE-2026-58249 at the time of writing. No public PoC, exploit code, or Nuclei template is available.