CVE-2025-10044 is a medium-severity security vulnerability identified in the Red Hat Build of Keycloak, an open-source identity and access management solution widely used for single sign-on and authentication services. The vulnerability arises from improper neutralization of input during web page generation, specifically involving the error_description query parameter in Keycloak's account console and other related pages. This parameter accepts arbitrary text input, which is then directly rendered on error pages without adequate validation or sanitization. Although HTML encoding is applied, which prevents classic cross-site scripting (XSS) attacks that execute malicious scripts, the vulnerability enables attackers to craft URLs containing misleading or deceptive messages. These messages can include fake support phone numbers, URLs, or other social engineering content displayed within the trusted Keycloak user interface. This creates a phishing vector where users may be tricked into contacting malicious actors or divulging sensitive information, leveraging the trust users place in the Keycloak UI. The vulnerability does not allow direct code execution or compromise of confidentiality but impacts the integrity of the user experience and could lead to social engineering attacks. The CVSS v3.1 base score is 4.3 (medium), reflecting that the attack vector is network-based, requires no privileges, but does require user interaction (clicking a crafted URL). There are no known exploits in the wild as of the publication date, and no patches or fixes have been linked yet. The flaw is primarily an issue of input validation and user interface trustworthiness rather than a direct technical compromise of Keycloak's core security functions.

For European organizations, the impact of this vulnerability is primarily related to phishing and social engineering risks rather than direct system compromise. Organizations relying on Red Hat Build of Keycloak for authentication and identity management may inadvertently present deceptive error messages to their users, potentially leading to users being misled into contacting fraudulent support channels or divulging credentials or other sensitive information. This could facilitate targeted phishing campaigns, credential theft, or unauthorized access if attackers leverage the trust in the Keycloak UI. The impact is particularly significant for sectors with high reliance on secure authentication, such as financial services, government, healthcare, and critical infrastructure, where identity compromise can have cascading effects. While the vulnerability does not allow remote code execution or data breach directly, the erosion of user trust and potential for social engineering attacks could lead to indirect breaches or fraud. Additionally, organizations with strict regulatory requirements under GDPR must consider the reputational and compliance risks associated with phishing incidents stemming from this vulnerability.

To mitigate this vulnerability, European organizations should implement the following specific measures: 1) Monitor for updates and patches from Red Hat and apply them promptly once available to ensure the vulnerability is remediated at the source. 2) Implement strict input validation and sanitization on the error_description parameter within any custom Keycloak deployments or integrations, ensuring that arbitrary text cannot be rendered without proper escaping or filtering. 3) Employ Content Security Policy (CSP) headers to restrict the types of content that can be loaded or executed within Keycloak pages, reducing the risk of malicious content execution. 4) Educate users and administrators about the potential phishing risks associated with misleading error messages and encourage verification of support contact details through official channels. 5) Use web application firewalls (WAFs) with custom rules to detect and block suspicious query parameters or URL patterns that attempt to exploit this vulnerability. 6) Conduct regular security assessments and penetration testing focusing on UI-based phishing vectors and input handling in authentication portals. 7) Consider implementing multi-factor authentication (MFA) to reduce the impact of credential compromise resulting from phishing attempts. These steps go beyond generic advice by focusing on both technical controls and user awareness tailored to the specific nature of this vulnerability.