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Netweaver AbapApplication · Sap

CVE-2021-27634

MEDIUM · 5.9 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 →
68/100
Remediation priority · Elevated
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 AS for ABAP (RFC Gateway), 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 - 7.22,8.04,7.49,7.53,7.73,7.77,7.81,7.82,7.83, 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 ThCpicDtCreate () 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 RFC Gateway contains an improper input validation vulnerability in the ThCpicDtCreate() method. An unauthenticated attacker can send a specially crafted packet over the network that triggers an internal error, causing the ABAP system to crash and become unavailable. This is a Denial of Service vulnerability with no data exfiltration or modification capability.

MitigationApply the relevant SAP Security Note to update the kernel patches. Implement network-level filtering to restrict unauthorized packets to the RFC Gateway ports as a compensating control until the patch can be applied.

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 AbapApplication
Affected:= kernel_7.22= kernel_7.49= kernel_7.53= kernel_7.73= kernel_8.04= krnl32nuc_7.22= krnl32nuc_7.22ext= krnl64nuc_7.22= krnl64nuc_7.22ext= krnl64nuc_7.49= krnl64uc_7.22= krnl64uc_7.22ext

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

CVSS:3.1/AV:N/AC:H/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. Identify the SAP kernel version
    Use SAP transaction SM51 to view the kernel release and patch level, or check the kernel executables on the application server (typically in /sapmnt/<SID>/exe or /usr/sap/<SID>/SYS/exe/run). The kernel version will appear as a release number like 7.22, 7.49, 7.53, 7.73, or 8.04.
    Affected if The kernel version matches one of the affected versions: kernel_7.22, kernel_7.49, kernel_7.53, kernel_7.73, kernel_8.04, krnl32nuc_7.22, krnl32nuc_7.22ext, krnl64nuc_7.22, krnl64nuc_7.22ext, krnl64nuc_7.49, krnl64uc_7.22, or krnl64uc_7.22ext.
  2. Verify the RFC Gateway is running
    Check if the RFC Gateway process (gwrd) is active on the SAP system. This can be done via transaction SM51 (process list) or by checking for the gateway process on the operating system.
    Affected if The RFC Gateway process is running and listening on network ports (typically sapgw00-sapgw99).
  3. Confirm network exposure of RFC Gateway ports
    Use netstat or ss commands to list listening ports. Look for ports in the sapgw* range (commonly 3300 for sapgw00, 3301 for sapgw01, etc.). Determine if these ports are bound to external interfaces or exposed to untrusted networks.
    Affected if The RFC Gateway ports are listening on external/accessible network interfaces and reachable from untrusted networks.

You are affected if your SAP system runs a kernel version matching the listed affected versions AND the RFC Gateway is exposed on accessible network ports.

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 Note to update the kernel patches. Implement network-level filtering to restrict unauthorized packets to the RFC Gateway ports as a compensating control until the patch can be applied.

Fix this in Netweaver Abap Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2021-27634 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
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