CVE-2026-101974 in Junos OS
Summary
by MITRE • 10/14/2026
An Improper Validation of Specified Quantity in Input vulnerability in rpd of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent OSPF peer to disclose rpd memory or cause a rpd crash via a malformed OSPF packets.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as improper validation of specified quantity in input within the Routing Protocol Daemon, known as rpd, represents a critical security flaw in Juniper Networks Junos OS and Junos OS Evolved platforms. This defect specifically impacts the Open Shortest Path First protocol implementation, allowing an attacker with adjacent network connectivity to exploit malformed OSPF packets for malicious purposes. The core technical issue stems from insufficient validation of packet fields that dictate data quantities or lengths during processing by rpd. When a neighboring router sends specially crafted OSPF messages containing invalid or excessively large quantity specifications, the daemon fails to properly verify these inputs against expected bounds before allocating memory or executing subsequent operations. This lack of rigorous input sanitization creates an environment where internal state management can be manipulated through external network traffic, bypassing standard security controls designed to protect routing infrastructure integrity.
From a technical perspective, this flaw enables two distinct attack vectors depending on the specific nature of the malformed packet and the version of the software involved. In one scenario, the improper validation allows for an out-of-bounds read operation, which can lead to the disclosure of sensitive information stored in rpd memory. By carefully crafting OSPF packets that trigger these invalid reads, a remote attacker adjacent to the vulnerable device may extract portions of internal process memory. This could potentially reveal cryptographic keys, routing table details, or other confidential data structures essential for network operations. In another scenario, particularly when the malformed input causes buffer overflows or logic errors during processing, the result is a denial of service condition characterized by a crash of the rpd process. Since rpd handles critical routing protocols including OSPF, BGP, and IS-IS, its failure can lead to significant disruption in network connectivity, loss of route advertisements, and potential instability across the entire autonomous system relying on that device for path computation and forwarding decisions.
The operational impact of this vulnerability is severe due to the central role rpd plays in Juniper routing platforms. An adjacent attacker does not require authentication or complex multi-hop traversal capabilities; simple layer 2 adjacency with an OSPF neighbor is sufficient to launch the attack. If memory disclosure occurs, it compromises confidentiality and potentially aids further exploitation by providing insights into system internals that can be leveraged for more sophisticated attacks against other services running on the device. Conversely, if a crash is induced, the immediate effect is a denial of service affecting all routing protocols managed by rpd. This results in temporary or prolonged loss of network reachability until the process restarts and routes are re-established through neighbor adjacencies. Such disruptions can cause cascading failures across interconnected networks, impacting business continuity and violating availability requirements mandated by various industry standards and compliance frameworks.
This vulnerability aligns with CWE-20 Improper Input Validation, as it involves a failure to correctly verify the integrity or validity of data received from an external source before processing. Additionally, it relates to CWE-125 Out-of-bounds Read when memory disclosure is possible, reflecting the unauthorized access to memory regions beyond intended boundaries. From an offensive security perspective, this flaw maps to MITRE ATT&CK technique T1078 Valid Accounts if exploited via compromised adjacent peers, or more broadly to network reconnaissance and disruption tactics under initial access and impact categories respectively. The ability to crash a critical daemon also corresponds to resource exhaustion attacks aimed at degrading service availability within enterprise networks.
Mitigation strategies must prioritize immediate patching of Junos OS and Junos OS Evolved installations with the latest vendor-released updates that address this specific rpd validation flaw. Organizations should verify their current software versions against advisory bulletins provided by Juniper Networks to determine applicability. In environments where patching is not immediately feasible, network segmentation strategies can help mitigate risk by restricting OSPF adjacency formation to trusted peers only and implementing strict access control lists on interfaces participating in routing protocol exchanges. Monitoring for anomalous OSPF traffic patterns or unexpected rpd restarts via syslog messages provides an additional layer of defense through detection capabilities. Regular audits of configuration settings ensuring that unnecessary services are disabled further reduce the attack surface available to potential adversaries seeking to exploit this weakness within the network infrastructure.