Go TLS HostnameError Resource Exhaustion via Cert
CVE-2025-61729 Published on December 2, 2025
Excessive resource consumption when printing error string for host certificate validation in crypto/x509
Within HostnameError.Error(), when constructing an error string, there is no limit to the number of hosts that will be printed out. Furthermore, the error string is constructed by repeated string concatenation, leading to quadratic runtime. Therefore, a certificate provided by a malicious actor can result in excessive resource consumption.
Vulnerability Analysis
CVE-2025-61729 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Products Associated with CVE-2025-61729
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Affected Versions
Go standard library crypto/x509:- Before 1.24.11 is affected.
- Version 1.25.0 and below 1.25.5 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.