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CVE-2020-23533

23
FAUCET Score

CVE-2020-23533 is a critical improper cryptographic signature verification vulnerability (CWE-347) affecting Union Pay versions up to 1.2.0. This flaw allows attackers to generate forged authentication codes due to a NULL secret key, enabling them to make unauthorized purchases on merchant websites and mobile applications. With a CVSS score of 7.5 (HIGH), it presents a significant risk, requiring no user interaction or authentication for exploitation. Despite its severity, there is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.2.0CPE matchmatch criteria
cpe:2.3:a:unionpayintl:union_pay:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.92%
Probability of exploitation in next 30 days
EPSS Percentile
56.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0092 is in the 31st percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

mobitec.ie.cuhk.edu.hk / cve_2020
Permissions Required
cwe.mitre.org / data/definitions/347.html
Technical Description
dropbox.com / s/6smwnbrp0kgsgrc/poc_code.py
Third Party Advisory
dropbox.com / s/czbkdr73tclq2nr/UnionPay_Vulnerability_Report.txt
Third Party Advisory