Debug logging is detailed diagnostic output used to help developers trace how an application behaves. It can include request bodies, headers, API keys, session IDs, cookies, stack traces, and other metadata that would normally stay hidden. In cyber security, this matters because logs are often copied into central storage, backups, SIEM platforms, or support tools, making a temporary debug record a long-lived data exposure risk.
Attackers look for debug logs because they can reveal credentials, prompts, tokens, internal endpoints, or the exact format of security checks. Defenders reduce this risk by disabling verbose logging in production, redacting sensitive fields, limiting who can read logs, and enforcing short retention. In AI systems and relay services, debug logging can accidentally preserve user prompts or upstream responses, turning routine troubleshooting into a privacy problem.