CVE-2025-65637

A denial-of-service vulnerability in github.com/sirupsen/logrus occurs when Entry.Writer() processes a single-line payload larger than 64KB with no newline characters. Due to a limitation in Go’s internal bufio.Scanner, the read operation fails with a “token too long” error, causing the underlying writer pipe to close. In affected versions, this leaves the Writer interface unusable and can disrupt logging functionality, potentially degrading application availability.

This vulnerability is categorized as Moderate because its impact is limited to the logging subsystem and requires a specific, non-default usage pattern to trigger—namely, sending a single unbounded line exceeding 64KB through Entry.Writer(). Most Logrus deployments do not expose this interface directly to attacker-controlled input, which raises the attack complexity and reduces realistic exploitability. Additionally, the flaw does not affect confidentiality or integrity, nor does it allow code execution or privilege escalation. The failure results in a controlled degradation of availability (logging becoming non-functional), rather than a broader application outage or systemic compromise. These constrained conditions and limited real-world impact justify treating the issue as moderate rather than important.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation is either unavailable or does not meet Red Hat Product Security standards for usability, deployment, applicability, or stability.