CVE-2021-33663Network attack vector

SMTP command injection via improper I/O buffering

Published Jun 9, 2021 · Updated Aug 3, 2024

Command injection in affected SAP NetWeaver AS ABAP kernel releases allows remote attackers to alter encrypted SMTP sessions. The kernel's SMTP TLS handling fails to restrict I/O buffering, allowing attacker-supplied cleartext commands to enter the encrypted session. No authentication or user interaction is required, and the reported consequence is limited to partial modification of application data carried through SMTP.

CVSS severity5.3
Medium
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in affected SAP NetWeaver AS ABAP kernel releases allows remote attackers to alter encrypted SMTP sessions. The kernel's SMTP TLS handling fails to restrict I/O buffering, allowing attacker-supplied cleartext commands to enter the encrypted session. No authentication or user interaction is required, and the reported consequence is limited to partial modification of application data carried through SMTP.

The record

CVE
CVE-2021-33663
Published
Jun 9, 2021
Updated
Aug 3, 2024
Vendor
SAP SE
Product
SAP NetWeaver AS ABAP
Classifications
T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 7.22
  2. Affected versionversion=< 7.22EXT
  3. Affected versionversion=< 7.49
  4. Affected versionversion=< 7.53
  5. Affected versionversion=< 7.73
  6. Affected versionversion=< 7.77
  7. Affected versionversion=< 7.81
  8. Affected versionversion=< 7.82
  9. Affected versionversion=< 7.83
  10. Affected versionversion=< 7.84
  11. Affected versionversion=< 8.04
  12. Affected versionversion=< KERNEL - 7.22
  13. Affected versionversion=< KRNL32NUC - 7.22
  14. Affected versionversion=< KRNL32UC - 7.22
  15. Affected versionversion=< KRNL64NUC - 7.22
  16. Affected versionversion=< KRNL64UC - 8.04

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SAP SE · SAP NetWeaver AS ABAPversion=< 7.22; version=< 7.22EXT; version=< 7.49; version=< 7.53; version=< 7.73; version=< 7.77; version=< 7.81; version=< 7.82; version=< 7.83; version=< 7.84; version=< 8.04; version=< KERNEL - 7.22; version=< KRNL32NUC - 7.22; version=< KRNL32UC - 7.22; version=< KRNL64NUC - 7.22; version=< KRNL64UC - 8.04

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
5.8SAP SECVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1565.002Transmitted Data Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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