A newly identified security flaw affects the logging package commonly used in web applications, allowing malicious actors to manipulate recorded entries and compromise log integrity. The vulnerability carries a medium severity rating, with a CVSS v3 score of 5.3 and a CVSS v4 score of 0.0, indicating that while confidentiality and availability remain unimpacted, integrity is moderately at risk over network connections without requiring special privileges or user interaction. Because previous patches failed to fully neutralize specific control characters and unescaped Unicode line separators within request tokens, log records can be split arbitrarily into multiple logical entries. Threat intelligence teams recommend immediate attention to prevent audit trail tampering and ensure reliable application monitoring across all affected systems.
CVE-2026-15603: The vulnerability stems from improper neutralization of input during web log generation, classified under CWE-117 for improper output neutralization for logs. The affected component is the widely deployed logging library used across Node-based applications to record incoming HTTP requests and responses. An attacker can exploit this flaw by injecting specific Unicode line separators and control code points through request headers, user agents, or target URLs. This manipulation tricks downstream log analysis tools into treating single log entries as multiple distinct records, effectively allowing unauthorized data injection or log forging.[/subscribe_to_unlock_form]
A newly identified security flaw affects the logging package commonly used in web applications, allowing malicious actors to manipulate recorded entries and compromise log integrity. The vulnerability carries a medium severity rating, with a CVSS v3 score of 5.3 and a CVSS v4 score of 0.0, indicating that while confidentiality and availability remain unimpacted, integrity is moderately at risk over network connections without requiring special privileges or user interaction. Because previous patches failed to fully neutralize specific control characters and unescaped Unicode line separators within request tokens, log records can be split arbitrarily into multiple logical entries. Threat intelligence teams recommend immediate attention to prevent audit trail tampering and ensure reliable application monitoring across all affected systems.
CVE-2026-15603: The vulnerability stems from improper neutralization of input during web log generation, classified under CWE-117 for improper output neutralization for logs. The affected component is the widely deployed logging library used across Node-based applications to record incoming HTTP requests and responses. An attacker can exploit this flaw by injecting specific Unicode line separators and control code points through request headers, user agents, or target URLs. This manipulation tricks downstream log analysis tools into treating single log entries as multiple distinct records, effectively allowing unauthorized data injection or log forging.[emaillocker id="1283"]
To address this security issue effectively, administrators and developers should implement the following mitigation steps:
We recommend you to update morgan to version 1.12.0.
The following reports contain further technical details:
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