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Message ServerApplication · Sap

CVE-2023-37491

HIGH · 8.8 CVSS v3.1 Published 2023-08-08
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The ACL (Access Control List) of SAP Message Server - versions KERNEL 7.22, KERNEL 7.53, KERNEL 7.54, KERNEL 7.77, RNL64UC 7.22, RNL64UC 7.22EXT, RNL64UC 7.53, KRNL64NUC 7.22, KRNL64NUC 7.22EXT, can be bypassed in certain conditions, which may enable an authenticated malicious user to enter the network of the SAP systems served by the attacked SAP Message server. This may lead to unauthorized read and write of data as well as rendering the system unavailable.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

The ACL (Access Control List) in SAP Message Server can be bypassed under certain conditions, allowing an authenticated malicious user to gain unauthorized network access to SAP systems served by the attacked message server. This enables potential unauthorized read/write operations on connected systems and could render them unavailable.

MitigationApply the relevant SAP security patches/notes for this vulnerability and review/configure ACL settings to ensure proper access controls are enforced on the SAP Message Server.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Message ServerApplication
Affected:= kernel_7.22= kernel_7.53= kernel_7.54= kernel_7.77= krnl64nuc_7.22= krnl64nuc_7.22ex= rnl64uc_7.22= rnl64uc_7.22ext= rnl64uc_7.53

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify SAP Message Server installation
    Locate the SAP Message Server process or executable in your environment. Common process names include 'msg_server', 'msgns', or check SAP kernel directories for the 'msg_server' executable.
    Affected if SAP Message Server is present in the environment
  2. Determine Message Server kernel version
    Run 'SAPCAR -tvf <kernel_archive>' on the SAP kernel files, or check the 'VERSION' file in the kernel directory, or use SAP transaction SMMS to view the Message Server version information.
    Affected if The kernel version matches one of the affected versions: kernel_7.22, kernel_7.53, kernel_7.54, kernel_7.77, krnl64nuc_7.22, krnl64nuc_7.22ex, rnl64uc_7.22, rnl64uc_7.22ext, or rnl64uc_7.53
  3. Check ACL configuration status
    Access SAP transaction SMMS (Message Server Monitor) or inspect the 'msg_server.acl' configuration file in the SAP kernel directory to determine if Access Control Lists are defined.
    Affected if ACL is configured on the message server (the bypass applies when ACL exists but can be circumvented)
  4. Review ACL entries and permitted hosts
    Examine the ACL configuration file (typically msg_server.acl or via transaction SMMS) to see which hosts/networks are permitted to connect to the message server.
    Affected if ACL entries exist and the server is accessible over network (vulnerability allows bypassing these controls)

You are affected if SAP Message Server is running with one of the listed kernel versions and has ACL configured, as the vulnerability allows bypassing those access controls.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the relevant SAP security patches/notes for this vulnerability and review/configure ACL settings to ensure proper access controls are enforced on the SAP Message Server.

Fix this in Message Server Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,980
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-37491 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data