CVE-2016-20030

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

ZKTeco ZKBioSecurity 3.0 suffers from a user enumeration vulnerability, identified as CVE-2016-20030 and associated with CWE-551. This flaw enables unauthenticated attackers to identify valid usernames by submitting partial character strings through the username parameter in requests to the authLoginAction!login.do script. The application responds differently to valid versus invalid inputs, allowing attackers to systematically discover active user accounts. The vulnerability has a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), reflecting its critical severity due to network accessibility and lack of prerequisites.

Unauthenticated remote attackers can exploit this vulnerability over the network with low complexity and no user interaction required. By crafting and sending multiple HTTP requests with incremental or partial username guesses to the login endpoint, attackers differentiate valid accounts based on response variations, such as timing, status codes, or error messages. Successful enumeration provides a list of legitimate usernames, which can facilitate subsequent attacks like targeted brute-force password guessing, credential stuffing, or social engineering.

Advisories from sources including IBM X-Force Exchange, Packet Storm Security, VulnCheck, and Zero Science (ZSL-2016-5366) document the issue and provide technical details on exploitation, though specific patch information or mitigation steps are referenced in those publications for further review by practitioners.