Secure Error Logging Practices to Prevent Information Leaks Across Java, Kotlin, JavaScript and Python
The article examines how improper error logging can expose sensitive details such as stack traces, file paths, library versions and database structures, enabling attackers to map applications and craft targeted exploits. It covers core logging levels from DEBUG to FATAL, mechanisms including text files, binary logs and databases, plus the roles of Trace ID and Correlation ID in tracing requests across microservices. Real-world vulnerable code examples in Flask and SQLite demonstrate direct exception output, manual traceback exposure and SQL error leakage that confirm technologies like Python 3.10 or SQLite usage. CWE categories including CWE-209, CWE-532, CWE-538 and CWE-1295 are referenced to classify risks of information disclosure through logs. Mitigation steps include stripping version headers in Nginx, sanitizing inputs with regular expressions, using OpenTelemetry for structured JSON logging and avoiding debug modes in production. The guidance stresses balancing detailed logs for incident response with protections against injection and reconnaissance.
HabrJul 30, 2026Translated from Russian