CVE-2025-61723 is a vulnerability classified under CWE-407 (Inefficient Algorithmic Complexity) found in the Go standard library's encoding/pem package. The issue arises because the parsing algorithm for PEM-encoded data exhibits non-linear processing time growth when handling certain malformed or invalid inputs. Specifically, as the size of crafted invalid PEM inputs increases, the CPU time required to parse them grows disproportionately, leading to potential resource exhaustion. This flaw can be exploited remotely without authentication or user interaction by sending specially crafted PEM data to applications that utilize the vulnerable Go library for PEM parsing, such as TLS certificate processing or cryptographic key handling. The vulnerability affects all Go versions from 0 up to and including 1.25.0. The CVSS v3.1 base score is 7.5, reflecting a high severity due to the network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability (denial of service). No known public exploits have been reported yet, but the vulnerability could be leveraged to cause denial-of-service conditions by overwhelming CPU resources, potentially disrupting critical services. The lack of a patch link indicates that a fix may still be pending or in development. Organizations using Go for services exposed to untrusted PEM inputs should be aware of this risk and prepare mitigation strategies.

The primary impact of CVE-2025-61723 is denial of service through resource exhaustion. European organizations that deploy Go-based applications or services parsing PEM-encoded data from untrusted sources—such as web servers, certificate management systems, or cryptographic tools—may experience service outages or degraded performance. This can affect availability of critical infrastructure, including secure communications and authentication services. Given the widespread use of Go in cloud-native environments, microservices, and DevOps tooling, the vulnerability could disrupt automated certificate renewal processes or security appliances that rely on PEM parsing. The impact is particularly significant for organizations with high volumes of external connections or those exposed to the internet, as attackers can remotely trigger the vulnerability without authentication. This could lead to operational downtime, increased incident response costs, and potential reputational damage. Confidentiality and integrity are not directly impacted, but availability degradation can indirectly affect business continuity and security posture.

To mitigate CVE-2025-61723, organizations should: 1) Monitor for and apply updates to the Go standard library as soon as a patch is released addressing this vulnerability. 2) Implement input validation to reject obviously malformed or excessively large PEM inputs before parsing. 3) Employ rate limiting and connection throttling on services that accept PEM data from untrusted sources to reduce exposure to resource exhaustion attacks. 4) Use resource monitoring and alerting to detect abnormal CPU usage patterns during PEM parsing operations. 5) Where possible, isolate PEM parsing functionality in separate processes or containers with resource limits to contain potential DoS effects. 6) Review and audit codebases to identify all usages of the encoding/pem package and assess exposure. 7) Consider fallback or alternative parsing libraries if patching is delayed. These steps go beyond generic advice by focusing on proactive input handling, resource control, and architectural isolation to reduce risk until official fixes are available.