Resource Consumption Vulnerability in Go's Error Handling

CVE-2025-61729

What is CVE-2025-61729?

CVE-2025-61729 is a resource consumption vulnerability found within the Go Standard Library, specifically in the HostnameError.Error() function. This function is responsible for generating error strings related to hostname resolution issues. The vulnerability arises because there is no limit enforced on the number of hosts that can be printed in the error string. Additionally, the method employed for constructing this error string utilizes repeated string concatenation, which results in a quadratic increase in runtime. Malicious actors can exploit this vulnerability by providing a crafted certificate that generates excessive resource utilization, potentially leading to denial-of-service scenarios. Organizations utilizing the Go programming language and its standard library may face significant operational impacts if their systems become overwhelmed by such resource consumption.

Potential impact of CVE-2025-61729

1. Denial of Service: The primary risk posed by this vulnerability is the potential for denial-of-service attacks. An attacker can craft a malicious certificate that results in excessive error string generation, consuming system resources and rendering services unusable.

2. Performance Degradation: Even in the absence of successful exploitation, the vulnerability can lead to considerable performance issues in applications that rely heavily on Go's error handling for hostname resolution. This can impact user experience and system reliability.

3. Increased Operational Costs: Organizations may incur higher operational costs due to the need for additional resources to handle unexpected high loads or to implement mitigative measures against this vulnerability. This includes potential downtime and the subsequent loss of productivity while addressing the issues caused by the vulnerability.

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