CVE-2022-39307 is a vulnerability in Grafana, an open-source monitoring and observability platform widely used for visualizing metrics and logs. The issue arises in the password reset functionality on the login page. Specifically, when an unauthenticated user submits a POST request to the `/api/user/password/sent-reset-email` endpoint with a username or email that does not exist in the system, the server responds with a JSON message explicitly stating “user not found.” This behavior leaks sensitive information by confirming the existence or non-existence of user accounts to unauthorized actors. Such information disclosure can facilitate targeted reconnaissance efforts by attackers, enabling them to identify valid usernames or email addresses registered in the system. This reconnaissance can be leveraged in subsequent attacks such as credential stuffing, phishing, or social engineering. The vulnerability affects Grafana versions from 9.0.0-beta1 up to but not including 9.2.4, and all versions prior to 8.5.15. The issue has been patched in Grafana 9.2.4 and backported to 8.5.15. There are no known workarounds, meaning users must upgrade to a fixed version to remediate the vulnerability. No exploits are currently known to be active in the wild, and the vulnerability is classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). The vulnerability does not require authentication or user interaction beyond submitting the password reset request, making it trivially exploitable by any unauthenticated user with network access to the Grafana instance. While the impact is limited to information disclosure, it can aid attackers in mapping valid user accounts, increasing the risk of further targeted attacks.

For European organizations, the exposure of valid user account information can undermine security by enabling attackers to conduct more effective credential-based attacks, such as brute force or credential stuffing, especially if users reuse passwords across services. Organizations relying on Grafana for critical infrastructure monitoring or operational dashboards may face increased risk of unauthorized access attempts. Although the vulnerability does not directly allow system compromise or data manipulation, the leaked information can be a stepping stone for attackers to escalate privileges or gain unauthorized access through other means. This is particularly concerning for sectors with high-value targets such as finance, energy, telecommunications, and government agencies in Europe, where Grafana is commonly deployed for monitoring IT and OT environments. Additionally, compliance with GDPR requires organizations to protect personal data; leaking user existence information could be considered a violation if it leads to further compromise or data breaches. The absence of known exploits reduces immediate risk, but the ease of exploitation and widespread use of Grafana in Europe necessitate prompt remediation to prevent potential reconnaissance and follow-on attacks.

The primary mitigation is to upgrade all affected Grafana instances to version 9.2.4 or later, or to 8.5.15 or later for the 8.x branch, where the vulnerability has been patched. Since no workarounds exist, patching is essential. Organizations should also audit their Grafana deployments to identify exposed instances accessible from untrusted networks and restrict access via network segmentation or firewall rules to trusted users only. Implementing Web Application Firewalls (WAFs) with custom rules to detect and block suspicious password reset requests may provide temporary protection. Monitoring logs for repeated password reset attempts can help detect reconnaissance activity. Additionally, organizations should enforce strong authentication policies, including multi-factor authentication (MFA) for Grafana access, to mitigate risks from credential-based attacks that may follow information disclosure. Regularly reviewing user accounts and removing inactive or unnecessary accounts reduces the attack surface. Finally, educating users about phishing and credential reuse risks complements technical controls.