CVE-2025-47912 is a vulnerability identified in the Go programming language's standard library, specifically within the net/url package's Parse function. According to RFC 3986, IPv6 addresses in URLs must be enclosed within square brackets in the host component, e.g., "http://[::1]/". However, IPv4 addresses and hostnames must not be enclosed in square brackets. The vulnerability arises because the Parse function does not enforce this syntactic rule, permitting non-IPv6 values, such as IPv4 addresses or hostnames, to be enclosed within square brackets. This improper validation (classified under CWE-1286) can cause the URL parser to accept malformed URLs that deviate from the standard. Such malformed URLs may lead to incorrect interpretation by applications, potentially causing security logic bypasses, incorrect routing, or other unexpected behaviors in software that depends on strict URL parsing. The vulnerability affects all Go versions from 0 up to and including 1.25.0. The CVSS v3.1 base score is 5.3 (medium severity), reflecting that the vulnerability can be exploited remotely without authentication or user interaction, impacting confidentiality to a limited extent but not integrity or availability. No known exploits have been reported in the wild as of the publication date (October 29, 2025). The lack of patch links suggests that a fix may be pending or recently released. This vulnerability is particularly relevant for developers and organizations using Go for web servers, proxies, or any networked applications that parse URLs, as improper URL parsing can be a vector for injection attacks, access control bypass, or other security issues.

For European organizations, the impact of CVE-2025-47912 depends largely on their use of the Go programming language in critical infrastructure, web services, or networked applications. Misinterpretation of URLs due to this vulnerability could lead to security bypasses, such as circumventing access controls or input validation mechanisms that rely on accurate URL parsing. This could expose sensitive data or allow unauthorized actions, impacting confidentiality. Although the vulnerability does not directly affect integrity or availability, the indirect consequences of malformed URL handling could facilitate further attacks or exploitation chains. Organizations in sectors with stringent data protection requirements, such as finance, healthcare, and government, may face compliance risks if this vulnerability is exploited. Additionally, software supply chains that incorporate Go-based components could propagate the risk if not updated. Given the medium severity and no current known exploits, the immediate risk is moderate but warrants proactive mitigation to prevent future exploitation.

European organizations should take the following specific mitigation steps: 1) Identify all applications and services using the Go standard library net/url package, particularly versions up to 1.25.0. 2) Monitor official Go project repositories and security advisories for patches addressing CVE-2025-47912 and apply updates promptly once available. 3) Implement additional input validation layers in applications that parse URLs, enforcing strict adherence to RFC 3986, especially ensuring that only IPv6 addresses are enclosed in square brackets. 4) Conduct code reviews and security testing focused on URL parsing logic to detect and remediate potential misuse or assumptions based on the flawed parsing behavior. 5) Employ runtime monitoring and anomaly detection to identify suspicious URL patterns or access attempts that exploit malformed URLs. 6) For critical systems, consider temporary workarounds such as sanitizing input URLs before parsing or using alternative parsing libraries until official patches are applied. 7) Educate developers about the implications of improper URL parsing and encourage secure coding practices around input validation.