Adminer before 5.4.3 fails to sanitize the server field before constructing a PDO DSN string, allowing unauthenticated attackers to inject ODBC parameters via semicolons. Attackers can inject TraceFile and TraceOn parameters to write PHP code to the web root, achieving remote code execution when the trace file is accessed.

CVE-2026-56705 affects Adminer versions before 5.4.3, which fails to sanitize the server field before constructing a PDO DSN string. This allows unauthenticated attackers to inject ODBC parameters using semicolons. By injecting TraceFile and TraceOn parameters, attackers can write arbitrary PHP code to the web root. When the resulting trace file is subsequently accessed via the web server, remote code execution is achieved. The vulnerability requires no authentication, making it particularly dangerous for publicly exposed Adminer instances. The fix is available in Adminer 5.4.3. The issue has been documented by both the GitHub security advisory and VulnCheck.