CVE-2025-47910 is a medium-severity vulnerability identified in the Go programming language's standard library, specifically within the net/http package version 1.25.0. The issue arises from improper access control related to the CrossOriginProtection feature. The vulnerability is triggered when the AddInsecureBypassPattern method is used. This method is intended to allow certain request patterns to bypass CrossOriginProtection checks. However, due to a flaw, it can bypass validation for more requests than intended. Consequently, CrossOriginProtection skips its security validation but forwards the original request path to be handled by a different HTTP handler. This other handler may not have the intended security protections, potentially exposing sensitive resources or functionality that should have been protected. The vulnerability is classified under CWE-284 (Improper Access Control), indicating that the access control mechanisms do not properly restrict access to resources. The CVSS 3.1 base score is 5.4 (medium), with vector AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N, meaning the attack can be performed remotely over the network with low attack complexity, requires no privileges but does require user interaction, and impacts confidentiality and integrity to a limited extent without affecting availability. No known exploits are currently in the wild, and no patches or fixes have been linked yet. This vulnerability could be exploited by an attacker who can trick a user into making a crafted HTTP request that bypasses CrossOriginProtection, potentially allowing unauthorized access or manipulation of data handled by other HTTP handlers in the application.

For European organizations, the impact of CVE-2025-47910 depends largely on their use of Go 1.25.0 in web applications that leverage the net/http package with CrossOriginProtection and the AddInsecureBypassPattern method. Organizations running web services that rely on this feature may inadvertently expose sensitive endpoints or data due to improper access control, leading to potential data leaks or unauthorized data modification. This can affect confidentiality and integrity of data, especially in sectors handling personal data (e.g., finance, healthcare, government) where GDPR compliance is critical. Although availability is not impacted, the breach of confidentiality or integrity could lead to regulatory penalties, reputational damage, and loss of customer trust. The requirement for user interaction (UI:R) means phishing or social engineering could be used to exploit this vulnerability, increasing risk in environments with less user security awareness. Since no known exploits are currently active, the immediate risk is moderate, but organizations should act proactively to prevent future exploitation.

European organizations should take the following specific mitigation steps: 1) Audit all Go-based web applications to identify usage of net/http version 1.25.0 and specifically check for implementations of CrossOriginProtection and AddInsecureBypassPattern. 2) Until an official patch is released, avoid using AddInsecureBypassPattern or disable CrossOriginProtection if feasible, to prevent unintended bypasses. 3) Implement additional access control checks at the application layer for sensitive endpoints to ensure that even if CrossOriginProtection is bypassed, unauthorized requests are blocked. 4) Employ strict input validation and logging to detect anomalous request patterns that may indicate exploitation attempts. 5) Educate users about phishing and social engineering risks since user interaction is required for exploitation. 6) Monitor official Go project channels for patches or updates and apply them promptly once available. 7) Consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious requests targeting vulnerable patterns. 8) Conduct penetration testing focusing on Cross-Origin Resource Sharing (CORS) and access control mechanisms to identify weaknesses related to this vulnerability.