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Netweaver As AbapApplication · Sap

CVE-2021-27631

HIGH · 7.5 CVSS v3.1 Published 2021-06-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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
SAP NetWeaver ABAP Server and ABAP Platform (Enqueue Server), versions - KRNL32NUC - 7.22,7.22EXT, KRNL64NUC - 7.22,7.22EXT,7.49, KRNL64UC - 8.04,7.22,7.22EXT,7.49,7.53,7.73, KERNEL - 7.22,8.04,7.49,7.53,7.73, allows an unauthenticated attacker without specific knowledge of the system to send a specially crafted packet over a network which will trigger an internal error in the system due to improper input validation in method EnqConvUniToSrvReq() causing the system to crash and rendering it unavailable. In this attack, no data in the system can be viewed or modified.

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 · high confidence

SAP NetWeaver ABAP Server Enqueue Server contains improper input validation in method EnqConvUniToSrvReq(). An unauthenticated remote attacker can send a specially crafted packet to trigger an internal error, causing the Enqueue Server to crash and making the system unavailable. No data exfiltration or modification is possible.

MitigationApply SAP Security Notes to patch the vulnerable Enqueue Server kernel. Additionally, restrict network access to the Enqueue Server port (typically port 32<system_id> + 98) using firewalls or ACLs to limit exposure to untrusted networks.

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
Netweaver As AbapApplication
Affected:= kernel_7.22= kernel_7.49= kernel_7.53= kernel_7.73= kernel_7.77= kernel_7.81= kernel_7.82= kernel_7.83= kernel_8.04= krnl32nuc_7.22= krnl32nuc_7.22ext= krnl64nuc_7.22

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
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Verify the Enqueue Server component is running
    Check if the Enqueue Server (ENQREP) process is active on the SAP system. In ABAP, this can be verified via transaction SMENQ or by checking process list for enqueue server processes (enserver.exe or similar).
    Affected if The Enqueue Server process is running and exposed to network traffic
  2. Identify the SAP kernel version
    On the SAP application server, check the kernel version by examining the executable version of the enqueue server binary (enserver.exe on Windows or enserver on Unix). The version is typically displayed in the binary's properties or via command line version flag.
    Affected if Kernel version matches one of the affected versions: 7.22, 7.49, 7.53, 7.73, 7.77, 7.81, 7.82, 7.83, 8.04 (for kernel_7* and kernel_8*), or 7.22, 7.22ext (for krnl32nuc and krnl64nuc variants)
  3. Confirm kernel variant matches affected types
    Identify the specific kernel type running (kernel_7*, kernel_8*, krnl32nuc, krnl64nuc) and cross-reference with the affected versions list provided in the CVE.
    Affected if The kernel variant and version combination appears in the CVE-affected version list
  4. Check network exposure of Enqueue Server port
    Verify that the Enqueue Server port (calculated as 32 + system_id, typically port 3298 for system ID 00) is accessible from untrusted networks. Use netstat or firewall rules to identify listening ports and their exposure.
    Affected if The Enqueue Server port is exposed to untrusted or public network segments

The system is affected if the Enqueue Server is running AND the SAP kernel version falls within the listed vulnerable versions (7.22, 7.49, 7.53, 7.73, 7.77, 7.81, 7.82, 7.83, 8.04 for kernel variants) AND the Enqueue Server port is accessible from untrusted networks.

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 SAP Security Notes to patch the vulnerable Enqueue Server kernel. Additionally, restrict network access to the Enqueue Server port (typically port 32<system_id> + 98) using firewalls or ACLs to limit exposure to untrusted networks.

Fix this in Netweaver As Abap Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA4.0 h
40.0 hours of engineering $7,000
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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-2021-27631 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