CVE-2026-102065 in Junos OS
Summary
by MITRE • 10/14/2026
An Improper Validation of Specified Quantity in Input vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a remote unauthenticated BGP peer to cause an rpd crash via a malformed BGP-signaled SRv6 service route when SRv6 dynamic tunnels are enabled.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified as Improper Validation of Specified Quantity in Input represents a critical security flaw within the routing protocol daemon, known as rpd, which is a core component of Juniper Networks Junos OS and Junos OS Evolved operating systems. This specific weakness arises from insufficient validation mechanisms when processing input data related to specified quantities during the parsing of Border Gateway Protocol (BGP) messages. The attack vector targets remote unauthenticated BGP peers who are able to establish sessions with the vulnerable device, exploiting the lack of rigorous checks on the size or quantity parameters embedded within these protocol exchanges. This flaw is particularly dangerous because it allows an attacker to trigger a denial-of-service condition without needing prior authentication credentials, thereby lowering the barrier for entry significantly in environments where BGP peering relationships are established openly or with weak security controls.
The technical mechanism of this vulnerability centers on the handling of Segment Routing over IPv6 (SRv6) service routes signaled via BGP when dynamic tunnel configurations are active within the network infrastructure. SRv6 is a modern networking technology that extends IP routing by embedding instructions in packet headers, and its implementation relies heavily on precise parsing of complex route attributes. When an unauthenticated peer sends a malformed BGP message containing specific SRv6 service routes with improperly formatted or excessively large quantity indicators, the rpd process fails to validate these inputs correctly. Instead of rejecting the invalid data gracefully, the daemon encounters an internal error state that leads to a crash. This behavior indicates a failure in boundary checking and resource allocation logic within the software's network stack processing routines, allowing external actors to disrupt the stability of the routing engine through crafted packet injection.
The operational impact of this vulnerability is severe, primarily manifesting as a denial-of-service condition for the affected Juniper device. A successful exploitation results in the crash of the rpd process, which is responsible for maintaining BGP sessions and computing routing tables. The restart or failure of this critical daemon can lead to temporary loss of connectivity, route flapping, or complete isolation from the network depending on the redundancy configurations present in the environment. For organizations relying on Junos OS for core infrastructure services, such instability poses a significant risk to business continuity and service availability. Furthermore, because the attack requires no authentication, it can be executed by any entity with network reachability to the BGP peer address, making it susceptible to widespread automated attacks across the internet if not properly mitigated through access control lists or other perimeter defenses.
From a classification perspective, this vulnerability aligns closely with CWE-20 Improper Input Validation and CWE-400 Uncontrolled Resource Consumption, as the root cause lies in the failure to validate input data before processing it into system resources. In terms of offensive security frameworks, this exploit maps to MITRE ATT&CK technique T1498 Network Denial of Service, specifically under subtechniques involving resource exhaustion or service disruption through protocol abuse. The lack of authentication requirement also highlights weaknesses in access control strategies for routing protocols, often categorized under CWE-287 Improper Authentication. Understanding these classifications helps security teams prioritize remediation efforts and align their defensive postures with industry-standard threat models to prevent similar exploitation patterns across network infrastructure components.
Mitigation strategies must focus on both immediate operational controls and long-term software updates. The most effective defense is the application of vendor-provided patches that address the input validation logic within the rpd component, ensuring that malformed BGP messages are correctly rejected without causing system instability. In environments where patching cannot be immediately implemented, network administrators should implement strict access control lists to restrict BGP peering sessions only to trusted and known IP addresses, thereby preventing unauthenticated peers from establishing connections with vulnerable devices. Additionally, enabling BGP authentication mechanisms such as MD5 or TCP-AO can add a layer of security that prevents unauthorized entities from participating in routing exchanges. Regular monitoring for unusual BGP traffic patterns and ensuring that SRv6 configurations are reviewed against current best practices will further reduce the attack surface associated with this vulnerability.