Directory traversal vulnerability in am.pl in (1) SQL-Ledger 2.6.27 and earlier, and (2) LedgerSMB before 1.2.0, allows remote attackers to run arbitrary executables and bypass authentication via a .. (dot dot) sequence and trailing NULL (%00) in the login parameter.  NOTE: this issue was reportedly addressed in SQL-Ledger 2.6.27, however third-party researchers claim that the file is still executed even though an error is generated.