CVE-2026-57032 in Junos OS
Summary
by MITRE • 07/10/2026
An Improper Handling of Undefined Parameters vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on EX Series devices allows an authenticated attacker with low privileges to cause a Denial-of-Service (DoS).
If an attempt is made to subscribe to an unsupported telemetry sensor path on EX2300, EX3400, EX4000, EX4100 and EX4400 via gRPC, this causes the FPC to crash. This leads to a complete service outage until the module has automatically restarted.
The following log message can be seen when this issue happens:
agentd[<PID>]: AGENTD_RESOURCE_NOT_FOUND: No resource name found for <sensor>
This issue affects Junos OS on
EX2300, EX3400, EX4000, EX4100 and EX4400
devices:
* all versions before 23.2R2-S7, * 23.4 versions before 23.4R2-S8, * 24.2 versions before 24.2R2-S5, * 24.4 versions before 24.4R2.
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Analysis
by VulDB Data Team • 07/10/2026
This vulnerability represents a critical improper handling of undefined parameters within the packet forwarding engine of Juniper Networks Junos OS on EX Series devices, classified under CWE-20 as "Improper Input Validation" and potentially mapping to ATT&CK technique T1499.1 for "Endpoint Denial of Service". The flaw manifests specifically when authenticated low-privileged users attempt to subscribe to unsupported telemetry sensor paths via gRPC interfaces on targeted hardware platforms. The vulnerability exploits a lack of proper parameter validation in the telemetry subsystem, where the system fails to gracefully handle undefined or unsupported sensor paths during subscription requests.
The technical execution of this vulnerability occurs through the gRPC communication channel where the packet forwarding engine receives malformed subscription requests containing non-existent telemetry sensor paths. When the system attempts to process these undefined parameters, it triggers an unhandled resource lookup failure that results in a complete crash of the Flexible Packet Forwarding Engine (FPC) module. This represents a classic example of improper error handling where the system does not implement adequate fallback mechanisms or validation procedures for unsupported telemetry endpoints. The specific error message "AGENTD_RESOURCE_NOT_FOUND: No resource name found for" indicates that the agent daemon fails to locate the requested telemetry resource and cannot properly recover from this condition.
The operational impact of this vulnerability is severe as it creates a complete service outage requiring manual intervention or automatic module restart procedures. The FPC crash terminates all forwarding operations on the affected module, disrupting network connectivity and data transmission across the entire device until the system automatically recovers through its built-in restart mechanisms. This denial-of-service condition affects critical network infrastructure components and can impact business continuity, particularly in environments where continuous network availability is essential for mission-critical operations.
Mitigation strategies should focus on implementing immediate software updates to patched versions as specified in the advisory, with particular attention to the version requirements: 23.2R2-S7, 23.4R2-S8, 24.2R2-S5, and 24.4R2. Organizations should also implement network monitoring to detect unauthorized gRPC subscription attempts and consider restricting access to telemetry interfaces through firewall rules or access control lists. Additionally, administrators should establish proactive monitoring for the specific error message patterns that precede system crashes, enabling early detection of potential exploitation attempts before full service outages occur.