CVE-2021-21478Network attack vector

User redirection via retained opener context

Published Feb 9, 2021 · Updated Aug 3, 2024

Reverse tabnabbing in SAP NetWeaver AS ABAP Web Dynpro allows remote attackers to redirect users to malicious sites. Links opened by Web Dynpro pages retain the opener browsing context, allowing the linked page to replace the original tab with a phishing page. Exploitation requires a user to open an attacker-controlled link; SAP reports redirection to phishing or malware-hosting pages.

CVSS severity4.7
Medium
EPSS probability0.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reverse tabnabbing in SAP NetWeaver AS ABAP Web Dynpro allows remote attackers to redirect users to malicious sites. Links opened by Web Dynpro pages retain the opener browsing context, allowing the linked page to replace the original tab with a phishing page. Exploitation requires a user to open an attacker-controlled link; SAP reports redirection to phishing or malware-hosting pages.

The record

CVE
CVE-2021-21478
Published
Feb 9, 2021
Updated
Aug 3, 2024
Vendor
SAP SE
Product
SAP NetWeaver AS ABAP
Classifications
CWE-601, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 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=< 701
  2. Affected versionversion=< 702
  3. Affected versionversion=< 731
  4. Affected versionversion=< 752
  5. Affected versionversion=< 753
  6. Affected versionversion=< 754
  7. Affected versionversion=< 755
  8. Affected versionversion=< 804
  9. Affected versionversion=< and SAP_BASIS 700
  10. Affected versionversion=< SAP_UI 750

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SAP SE · SAP NetWeaver AS ABAPversion=< 701; version=< 702; version=< 731; version=< 752; version=< 753; version=< 754; version=< 755; version=< 804; version=< and SAP_BASIS 700; version=< SAP_UI 750

Published CVSS scores

5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N
4.7SAP SECVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/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.

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

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

CWE-601URL Redirection to Untrusted Site ('Open Redirect')
T1204.001User Execution: Malicious Link

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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