CVE-2026-102184 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 Evolved platforms allows a configured EVPN signaling peer to cause an rpd crash via a malformed SRv6 structure carried in an EVPN route update. The result is a denial of service affecting routing adjacencies.
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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 Juniper Networks Junos OS and Junos Evolved platforms represents a critical flaw in the handling of Segment Routing over IPv6 (SRv6) structures during Ethernet Virtual Private Network (EVPN) signaling. This issue resides specifically within the routing protocol daemon, commonly referred to as rpd, which is responsible for managing dynamic routing protocols and maintaining network topology information. The root cause lies in insufficient validation mechanisms when processing incoming EVPN route updates that contain SRv6 encapsulation data. Specifically, the software fails to adequately verify the length or quantity of specified fields within these malformed structures before attempting to process them. This lack of rigorous input sanitization allows an attacker who has established a configured BGP peering relationship with the affected device to inject specially crafted packets containing invalid SRv6 parameters.
From a technical perspective, this vulnerability exploits the trust inherent in BGP peer configurations by leveraging the complexity of EVPN and SRv6 protocols. When a malicious or compromised signaling peer sends an EVPN route update featuring a malformed SRv6 structure, the rpd process attempts to parse the data without correctly checking for boundary conditions or logical consistency. The absence of proper bounds checking leads to memory corruption or logic errors within the daemon's execution flow. Because routing daemons are high-privilege processes that manage critical network infrastructure state, such internal failures typically result in an immediate termination of the rpd process. This crash is not merely a software glitch but a direct compromise of the device's ability to maintain its control plane functions.
The operational impact of this vulnerability is severe and primarily manifests as a Denial of Service (DoS) condition affecting routing adjacencies. When the routing protocol daemon crashes, the Junos OS or Junos Evolved platform loses its dynamic routing capabilities until the process is restarted by the system's watchdog mechanisms. During this outage period, the device cannot exchange route updates with its neighbors, leading to a temporary loss of connectivity for traffic relying on those specific routes. In environments where high availability and rapid convergence are critical, such as in service provider networks or large enterprise data centers, repeated crashes can lead to significant network instability, packet loss, and potential cascading failures if other nodes attempt to reroute traffic through unstable paths while the affected node is recovering.
This vulnerability aligns with CWE-20 Improper Input Validation, specifically regarding the failure to verify that input quantities or lengths are within expected limits before processing. It also maps to MITRE ATT&CK technique T1498 Network Denial of Service, as it enables an attacker to disrupt network availability by exhausting system resources through a crafted packet rather than brute-force volume attacks. The attack vector is classified as remote with low complexity but requires authentication or prior configuration trust, meaning the adversary must already have access to the BGP peering session. This highlights the importance of securing routing protocols and validating all inputs even from trusted peers, as insider threats or compromised peer devices can exploit these logical flaws.
Mitigation strategies for this vulnerability involve applying vendor-provided software patches that address the input validation logic within the rpd component. Administrators should ensure their Junos OS and Junos Evolved installations are updated to versions where this specific flaw has been remediated. In addition to patching, network operators can implement defense-in-depth measures such as strict access control lists (ACLs) on BGP peering sessions to restrict connections only to verified and trusted IP addresses. Furthermore, enabling BGP authentication using MD5 or TCP Authentication Option (TCP-AO) adds a layer of integrity verification that can prevent unauthorized peers from sending malicious route updates. Regular monitoring of system logs for rpd restart events is also recommended to detect potential exploitation attempts early, allowing for rapid incident response and restoration of normal routing operations.