CyberSecBulletin
CVE-2026-58240NVD status: Awaiting Analysis

SAP NetWeaver (Message Server): Use of Single-factor Authentication

Published Updated By the CyberSecBulletin desk

CVE-2026-58240 is a critical-severity use of single-factor authentication vulnerability in SAP NetWeaver (Message Server) from SAP, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected SAP NetWeaver (Message Server) versions: KERNEL 9.16; 9.18; 9.19, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.53% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Check which version of SAP NetWeaver (Message Server) you run against the affected versions below, and install the vendor's latest release.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
SAPSAP NetWeaver (Message Server)KERNEL 9.16; 9.18; 9.19; 9.20Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (sap.com).

Official description

SAP NetWeaver Message Server does not sufficiently validate the authenticity of internal application server components during registration. An unauthenticated attacker with network access to the affected service could exploit this weakness to register an unauthorized component and potentially perform unauthorized actions within the application environment, resulting in a high impact on the confidentiality, integrity, and availability of the affected system.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use of Single-factor Authentication

The product uses an authentication algorithm that uses a single factor (e.g., a password) in a security context that should require more than one factor.

How developers prevent this class of flaw

  • Use multiple independent authentication schemes, which ensures that -- if one of the methods is compromised -- the system itself is still likely safe from compromise. For this reason, if multiple schemes are possible, they should be implemented and required -- especially if they are easy to use.

More Use of Single-factor Authentication vulnerabilities (CWE-308)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use of Single-factor Authentication vulnerabilities

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