# CVE-2016-20030

## Summary

- **CVE ID:** CVE-2016-20030
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-551
- **Published:** Mar 15, 2026
- **Last Modified:** Jul 28, 2026

## Description

ZKTeco ZKBioSecurity 3.0 contains a user enumeration vulnerability that allows unauthenticated attackers to discover valid usernames by submitting partial characters via the username parameter. Attackers can send requests to the authLoginAction!login.do script with varying username inputs to enumerate valid user accounts based on application responses.

## Affected Products

- ZKTeco Inc. — ZKTeco ZKBioSecurity (3.0.1.0_R_230)

## References

- [CNA](https://www.zeroscience.mk/en/vulnerabilities/ZSL-2016-5366.php)
- [CNA](https://exchange.xforce.ibmcloud.com/vulnerabilities/116485)
- [CNA](https://packetstormsecurity.com/files/138573)
- [CNA](https://www.vulncheck.com/advisories/zkteco-zkbiosecurity-user-enumeration-via-authloginaction)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.56%
- **EPSS Percentile:** 45.3

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._