CVE-2025-46421 is a vulnerability identified in libsoup, a GNOME HTTP client/server library widely used in Linux environments, including Red Hat Enterprise Linux 10. The flaw arises when libsoup clients handle HTTP redirects. Specifically, when an HTTP redirect response is received, the client erroneously forwards the HTTP Authorization header to the new host specified in the redirect. This behavior is problematic because the Authorization header often contains sensitive credentials such as bearer tokens or basic authentication credentials. By sending these credentials to an unintended host, the redirected server can impersonate the user to the original host that issued the redirect, potentially gaining unauthorized access to protected resources. The vulnerability is classified with a CVSS v3.1 score of 6.8 (medium severity), reflecting the significant confidentiality and integrity impact but with some exploitation barriers. The attack vector is network-based (AV:N), requires no privileges (PR:N), but does require user interaction (UI:R) since the client must follow a redirect. The attack complexity is high (AC:H), indicating that exploitation is not trivial. The scope remains unchanged (S:U), meaning the impact is limited to the vulnerable component. There is no known exploit in the wild at the time of publication. This vulnerability can lead to credential leakage and unauthorized access, undermining trust in HTTP redirects and potentially enabling further attacks such as session hijacking or privilege escalation within affected systems.

For European organizations, this vulnerability poses a risk primarily to systems and applications relying on libsoup for HTTP communications, especially those running Red Hat Enterprise Linux 10. Confidential information such as authentication tokens or credentials could be exposed to malicious redirect endpoints, leading to unauthorized access to internal services or sensitive data. This could affect web services, APIs, or internal tools that use libsoup for HTTP requests. The impact is heightened in environments where redirects are common or where users interact with untrusted or external web resources. Organizations in sectors such as finance, healthcare, government, and critical infrastructure could face increased risk due to the sensitivity of their data and regulatory requirements around data protection. Additionally, the vulnerability could be exploited as part of a multi-stage attack chain, facilitating lateral movement or privilege escalation. The medium severity rating suggests that while the vulnerability is serious, exploitation requires specific conditions and user interaction, somewhat limiting widespread impact. However, the potential for credential theft and impersonation means that organizations must address this promptly to maintain security and compliance.

To mitigate CVE-2025-46421 effectively, organizations should: 1) Apply patches or updates from Red Hat or the libsoup project as soon as they become available to correct the improper forwarding of Authorization headers during redirects. 2) Implement strict validation and whitelisting of redirect URLs within applications to prevent redirects to untrusted or external domains. 3) Configure HTTP clients or applications using libsoup to disable automatic forwarding of Authorization headers on redirects where possible. 4) Employ network-level controls such as web proxies or firewalls to monitor and restrict suspicious redirect traffic. 5) Educate users and developers about the risks of following untrusted redirects and encourage cautious behavior when interacting with web resources. 6) Conduct security audits and penetration testing focusing on HTTP redirect handling and authorization header exposure. 7) Monitor logs for anomalous authentication attempts or unusual redirect patterns that could indicate exploitation attempts. These steps go beyond generic advice by focusing on configuration changes, user awareness, and proactive monitoring tailored to the specifics of this vulnerability.