CVE-2025-11537 identifies a security vulnerability in the Red Hat Build of Keycloak, an open-source identity and access management solution. The flaw arises when the logging format is configured to a verbose, user-supplied pattern such as the predefined 'long' pattern. Under these configurations, sensitive HTTP headers including Authorization and Cookie are logged in cleartext within application logs. These headers often contain bearer tokens or session cookies that serve as authentication credentials. If an attacker gains read access to these logs, they can extract these credentials and use them to impersonate legitimate users, potentially leading to full account compromise. The vulnerability requires that the attacker has some level of local or limited privileges to access the log files, as well as user interaction to enable or trigger verbose logging. The CVSS 3.1 score of 5.0 reflects a medium severity, considering the attack vector is local (AV:L), with low attack complexity (AC:L), requiring privileges (PR:L) and user interaction (UI:R). The impact on confidentiality is high (C:H), but integrity and availability are not affected (I:N, A:N). There are no known exploits in the wild at the time of publication, and no patches or mitigation links are provided in the source data. This vulnerability highlights the risk of improper output neutralization in logging mechanisms, emphasizing the need to avoid logging sensitive authentication data in verbose logs.

The primary impact of this vulnerability is the potential disclosure of sensitive authentication credentials through application logs. If an attacker can read the logs, they can extract bearer tokens or session cookies and impersonate users, leading to unauthorized access and full account compromise. This can result in unauthorized data access, privilege escalation, and potential lateral movement within an organization's network. Although the vulnerability does not affect system availability or integrity directly, the confidentiality breach can have severe consequences including data breaches, regulatory non-compliance, and reputational damage. Organizations relying on Keycloak for identity management and authentication are at risk, especially if log files are not adequately protected or if verbose logging is enabled in production environments. The requirement for local or limited privileges to access logs somewhat limits the attack scope, but insider threats or attackers who have gained initial footholds could exploit this vulnerability to escalate access.

To mitigate this vulnerability, organizations should immediately review and adjust their logging configurations to avoid using verbose or user-supplied patterns that log sensitive headers such as Authorization and Cookie. Specifically, disable or modify the 'long' logging pattern or any custom patterns that include sensitive data. Access controls on log files must be strictly enforced to ensure that only authorized personnel can read them, employing least privilege principles. Implement log monitoring and alerting to detect unusual access patterns or attempts to read logs. Consider encrypting log files at rest and in transit to reduce the risk of unauthorized disclosure. Regularly audit logging configurations and access permissions as part of security hygiene. If possible, update to a patched version of Keycloak once available from Red Hat. Additionally, educate administrators and developers about the risks of logging sensitive information and incorporate secure logging practices into development and deployment workflows.