CVE-2025-4922 is a high-severity vulnerability affecting HashiCorp Nomad, a popular workload orchestrator used for deploying and managing applications across distributed infrastructure. The vulnerability arises from an incorrect privilege assignment due to prefix-based Access Control List (ACL) policy lookups. Specifically, Nomad's ACL system uses prefix matching to determine which policies apply to a given request. However, this prefix-based lookup can cause incorrect rule application and shadowing, meaning that some ACL rules may be inadvertently overridden or bypassed by other rules with overlapping prefixes. This flaw can lead to unauthorized privilege escalation where users or services gain higher access rights than intended. The vulnerability affects Nomad Community Edition version 1.4.0 and earlier, as well as Nomad Enterprise editions prior to the fixed versions 1.10.2, 1.9.10, and 1.8.14. The CVSS v3.1 score of 8.1 reflects a high impact on confidentiality and integrity, with network attack vector, low attack complexity, and requiring only low privileges but no user interaction. Exploiting this vulnerability allows an attacker with some level of access to Nomad to escalate privileges and potentially access or modify sensitive workload scheduling and management data. Although no known exploits are currently reported in the wild, the vulnerability's nature and high severity score indicate a significant risk if left unpatched. The root cause is classified under CWE-266 (Incorrect Privilege Assignment), emphasizing the improper enforcement of security policies within the ACL mechanism. Organizations using affected Nomad versions should prioritize upgrading to the patched releases to prevent unauthorized access and privilege escalation risks.

For European organizations, the impact of CVE-2025-4922 can be substantial, especially those relying on HashiCorp Nomad for critical workload orchestration in cloud-native or hybrid environments. Unauthorized privilege escalation could lead to unauthorized access to sensitive application deployments, manipulation of workload scheduling, and potential exposure or tampering of confidential data. This could disrupt business operations, violate data protection regulations such as GDPR, and damage organizational reputation. Given Nomad's role in managing distributed applications, exploitation could also facilitate lateral movement within networks, increasing the risk of broader compromise. The vulnerability's network-based attack vector and lack of user interaction requirement make it easier for attackers to exploit remotely once they have low-level access, increasing the threat surface. European organizations in sectors such as finance, telecommunications, and critical infrastructure, which often use Nomad for scalable and resilient application deployment, are particularly at risk. Additionally, compliance requirements in Europe mandate strict access controls and incident response, so failure to address this vulnerability could result in regulatory penalties.

To mitigate CVE-2025-4922, European organizations should immediately upgrade affected Nomad installations to the patched versions: Nomad Community Edition 1.10.2 or later, and Nomad Enterprise 1.10.2, 1.9.10, or 1.8.14 or later. Beyond patching, organizations should audit their ACL policies to identify and correct any overlapping or ambiguous prefix rules that could cause shadowing or unintended privilege grants. Implement strict role-based access controls with the principle of least privilege to limit the impact of any potential privilege escalation. Regularly review and test ACL configurations using automated tools or scripts to detect policy conflicts. Network segmentation and monitoring should be enhanced to detect anomalous access patterns to Nomad servers. Employ logging and alerting on ACL-related events to quickly identify suspicious privilege changes. Finally, conduct security awareness and training for administrators managing Nomad ACLs to prevent misconfigurations that could exacerbate this vulnerability.