CVE-2020-36284Public exploitNetwork attack vector

Unauthenticated payment forgery via null MAC key

Published Apr 6, 2021 · Updated Aug 4, 2024

Improper signature verification in Union Pay Android SDK 3.4.93.4.9 and earlier allows remote attackers to forge payment results. The SDK selects MAC validation from attacker-controlled signMethod data and hashes a null secureKey when configuration omits that key, accepting forged messages at merchant notification endpoints. Remote unauthenticated attackers can submit crafted payment notifications and obtain goods or services without payment; the documented impact is transaction integrity loss rather than data disclosure or service interruption.

CVSS severity7.5
High
EPSS probability0.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in Union Pay Android SDK 3.4.93.4.9 and earlier allows remote attackers to forge payment results. The SDK selects MAC validation from attacker-controlled signMethod data and hashes a null secureKey when configuration omits that key, accepting forged messages at merchant notification endpoints. Remote unauthenticated attackers can submit crafted payment notifications and obtain goods or services without payment; the documented impact is transaction integrity loss rather than data disclosure or service interruption.

The record

CVE
CVE-2020-36284
Published
Apr 6, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 6, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NVDAV:N/AC:L/Au:N/C:N/I:P/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 exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1190Exploit Public-Facing Application

Public exploit references

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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