CVE-2025-62168 is a critical security vulnerability affecting Squid, a widely used web caching proxy, in versions prior to 7.2. The root cause is the failure to properly redact HTTP authentication credentials from error messages generated during failure handling. Specifically, when Squid encounters an error, it may include sensitive authentication tokens or credentials in the error message content sent to clients or administrators, which can be intercepted by malicious scripts. This vulnerability enables remote attackers to bypass browser security mechanisms, such as same-origin policies, to extract these credentials without requiring any authentication or user interaction. The leaked credentials can include tokens used internally by web applications behind Squid acting as a backend load balancer, potentially allowing attackers to impersonate trusted clients or escalate privileges. The vulnerability is classified under CWE-209 (Generation of Error Message Containing Sensitive Information) and CWE-550 (Exposure of Sensitive Information to an Unauthorized Actor). The CVSS v3.1 base score is 10.0 (critical), reflecting its high impact on confidentiality and integrity with network attack vector, no privileges required, and no user interaction needed. Although no exploits have been reported in the wild yet, the ease of exploitation and severity make it a significant threat. The issue is resolved in Squid version 7.2. As an interim mitigation, administrators can disable debug information in error emails by setting 'email_err_data off' in squid.conf, reducing the risk of credential leakage through error handling mechanisms.

For European organizations, this vulnerability poses a severe risk to the confidentiality and integrity of sensitive authentication credentials used in web infrastructure. Organizations relying on Squid as a caching proxy or backend load balancer may inadvertently expose internal authentication tokens to remote attackers, enabling unauthorized access to protected resources and potential lateral movement within networks. This can lead to data breaches, compromise of internal applications, and disruption of business operations. Given the critical CVSS score and the lack of required authentication or user interaction, the threat can be exploited at scale, especially in environments with internet-facing Squid proxies. The exposure of credentials can also undermine trust in secure communications and compliance with data protection regulations such as GDPR, potentially resulting in legal and financial penalties. The impact is heightened for sectors with stringent security requirements, including finance, healthcare, and government agencies across Europe.

European organizations should immediately upgrade all Squid installations to version 7.2 or later to fully remediate this vulnerability. Until patching is feasible, administrators should configure 'email_err_data off' in squid.conf to disable the inclusion of debug information in error emails, thereby reducing the risk of credential leakage. It is also advisable to audit existing Squid configurations to ensure no sensitive information is exposed via error handling or logging mechanisms. Network segmentation and strict access controls should be enforced to limit exposure of Squid proxies to untrusted networks. Monitoring and alerting for unusual access patterns or error message requests can help detect exploitation attempts. Additionally, organizations should review and rotate any potentially compromised credentials and tokens used in backend applications behind Squid. Incorporating these specific mitigations alongside general security best practices will reduce the attack surface and protect sensitive authentication data.