CVE-2026-57028: Juniper Junos OS Evolved License Exhaustion via Improper Communication Channel Restriction

A vulnerability, tracked as CVE-2026-57028, has been identified in Juniper Networks Junos OS Evolved. This flaw allows an unauthenticated, network-based attacker to cause license exhaustion, effectively leading to a denial-of-service condition. The issue stems from an improper restriction of communication channels, where an internal process, intended only for intra-device communication, becomes reachable over the network via an open port. This exposure grants unauthorized access to the device's license management system. All versions of Junos OS Evolved prior to 23.2R2-EVO are affected. Defenders should prioritize patching to prevent potential service disruptions and maintain the availability of critical network infrastructure.

Attack Chain

1. An unauthenticated attacker identifies a Juniper Networks Junos OS Evolved device with a vulnerable version (prior to 23.2R2-EVO) exposed to the network.
2. The attacker discovers an internal process port that is incorrectly accessible over the network due to improper initialization within Junos OS Evolved.
3. The attacker initiates a connection to this exposed internal port, leveraging its unintended network accessibility.
4. Through this connection, the attacker bypasses intended communication restrictions and gains unauthorized access to the device's internal license management system.
5. The attacker sends specific requests to the compromised license management process, designed to manipulate its state or consume resources.
6. These malicious interactions trigger a rapid depletion or exhaustion of the device's operational licenses.
7. The license exhaustion leads to a denial of service (DoS) condition, disrupting critical network functions and device availability.

Impact

Successful exploitation of CVE-2026-57028 results in license exhaustion on the affected Juniper Networks Junos OS Evolved devices. This condition directly leads to a denial of service, severely impacting the availability and functionality of critical network infrastructure. Organizations relying on these devices for core networking services could experience significant downtime, operational disruption, and potential financial losses due to service unavailability. The vulnerability affects all versions before 23.2R2-EVO, making a broad range of installations susceptible to this availability impact.

Recommendation

• Immediately apply the security update to upgrade Juniper Networks Junos OS Evolved to version 23.2R2-EVO or later, as specified for CVE-2026-57028.
• Review network segmentation and firewall rules to restrict access to internal device ports, limiting the attack surface for vulnerabilities like CVE-2026-57028 by preventing unauthenticated network access to internal processes.