CVE-2026-102026 in Junos OS
Summary
by MITRE • 10/14/2026
An Improper Control of a Resource Through its Lifetime vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent eBGP peer to cause a routing-daemon crash via a BGP route update when RIB sharding is enabled.
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Analysis
by VulDB Data Team • 10/14/2026
The identified vulnerability represents a critical flaw within the routing protocol daemon, known as rpd, of Juniper Networks Junos Operating System and Junos OS Evolved platforms. This specific weakness falls under the category of Improper Control of a Resource Through its Lifetime, which is formally classified in the Common Weakness Enumeration framework as CWE-401. The core technical issue arises from an improper handling of memory resources during the lifecycle management of routing information base structures when RIB sharding functionality is active. RIB sharding is a performance optimization feature designed to distribute routing table entries across multiple worker processes to enhance scalability and reduce latency in large-scale network environments. However, under specific conditions triggered by incoming Border Gateway Protocol route updates from an adjacent external BGP peer, the daemon fails to correctly manage or release allocated memory resources associated with these routes. This mismanagement leads to a state where the routing process encounters a fatal error, resulting in an immediate crash of the rpd service.
From an operational perspective, the impact of this vulnerability is severe and directly affects network stability and availability. When the routing protocol daemon crashes on a Juniper device running vulnerable versions of Junos OS or Junos OS Evolved, the router loses its ability to process dynamic routing updates effectively. This disruption can lead to temporary loss of connectivity for routes that rely on BGP for path selection. In environments where high availability is critical, such as service provider networks or large enterprise backbones, a crash in rpd may trigger redundant failover mechanisms if configured, but it introduces significant risk of transient black holes or routing loops during the restart period. Furthermore, repeated exploitation could lead to resource exhaustion on the control plane, potentially affecting other network services hosted on the same device. The vulnerability specifically requires an adjacent eBGP peer to exploit, meaning that a remote attacker must have direct connectivity to the affected router's BGP session interface and possess valid credentials or access to send crafted BGP updates.
The exploitation vector aligns with several tactics in the MITRE ATT&CK framework, particularly those related to network service discovery and disruption of availability. An adversary could leverage this flaw as part of a broader denial-of-service campaign aimed at degrading network infrastructure performance without necessarily gaining persistent access or exfiltrating data. The attack involves sending malformed or specifically crafted BGP route update messages that trigger the memory management error within the rpd process. Because the vulnerability is tied to RIB sharding, it highlights the risks associated with complex stateful processing in high-performance routing engines where resource isolation between shards may not be sufficiently robust against malicious inputs. This underscores the importance of rigorous input validation and strict lifecycle management for dynamically allocated resources even when performance optimizations are enabled.
Mitigation strategies primarily involve applying vendor-supplied software updates that address the underlying memory handling logic within the rpd component. Administrators should ensure their Juniper devices are running patched versions of Junos OS or Junnos OS Evolved where this issue has been resolved. In scenarios where immediate patching is not feasible, network segmentation and access control lists can be employed to restrict BGP peering sessions only to trusted adjacent peers, thereby reducing the attack surface for potential exploitation. Additionally, enabling monitoring tools that detect abnormal routing updates or frequent daemon restarts can aid in early detection of attempted exploits. It is also advisable to review RIB sharding configurations to ensure they are necessary and properly tuned, as disabling this feature may eliminate the specific code path vulnerable to this flaw, albeit at the cost of reduced scalability for very large routing tables. Regular security audits and adherence to CIS benchmarks for network device configuration can further harden the environment against such resource exhaustion attacks.