OpenEMR before 8.5.0 contains an authenticated SQL injection vulnerability in the Syndromic Surveillance module that allows users with Clinician-level privileges to read and modify arbitrary database contents by submitting crafted values in the form_icd_codes[] POST parameter to the syndromicsurveillance/index endpoint. Attackers can inject an unquoted numeric IN() clause and UNION DISTINCT SELECT statement using hex-encoded literals to abuse MySQL extractvalue() for error-based exfiltration of bcrypt password hashes and execute stacked queries that reset passwords, resulting in full administrative account takeover.