CVE-2021-27610Network attack vector

Unauthenticated user impersonation via RFC loopback reflection

Published Jun 16, 2021 · Updated Aug 3, 2024

Improper authentication in SAP NetWeaver AS ABAP and ABAP Platform allows remote attackers to gain illegitimate system access. System-internal RFC and HTTP communication fails to distinguish same-system application servers from external clients, allowing reflected connections to reuse leaked logon material. Exploitation requires an ordinary request from a vulnerable system that exposes reusable logon material; successful impersonation grants the victim user's privileges and can compromise the system.

CVSS severity9.0
Critical
EPSS probability1.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in SAP NetWeaver AS ABAP and ABAP Platform allows remote attackers to gain illegitimate system access. System-internal RFC and HTTP communication fails to distinguish same-system application servers from external clients, allowing reflected connections to reuse leaked logon material. Exploitation requires an ordinary request from a vulnerable system that exposes reusable logon material; successful impersonation grants the victim user's privileges and can compromise the system.

The record

CVE
CVE-2021-27610
Published
Jun 16, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-287, T1078
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.0SAP SECVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1078Valid Accounts

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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