CVE-2021-20866: Advancedcustomfields Advanced Custom Fields

Medium severity, CVSS 6.5. EPSS: 1.8% chance of exploitation in the next 30 days.

Advanced Custom Fields versions prior to 5.11 and Advanced Custom Fields Pro versions prior to 5.11 contain a missing authorization vulnerability in obtaining the user list which may allow a user to obtain the unauthorized information via unspecified vectors.

Affected products

• Advancedcustomfields Advanced Custom Fields: before 5.11 (fixed in 5.11)

Published 2021-12-13. Last modified 2026-06-17.