CVE-2019-0049 in Junos
Summary
by MITRE
On Junos devices with the BGP graceful restart helper mode enabled or the BGP graceful restart mechanism enabled, a certain sequence of BGP session restart on a remote peer that has the graceful restart mechanism enabled may cause the local routing protocol daemon (RPD) process to crash and restart. Repeated crashes of the RPD process can cause prolonged Denial of Service (DoS). Graceful restart helper mode for BGP is enabled by default. No other Juniper Networks products or platforms are affected by this issue. Affected releases are Juniper Networks Junos OS: 16.1 versions prior to 16.1R7-S3; 16.2 versions prior to 16.2R2-S9; 17.1 versions prior to 17.1R3; 17.2 versions prior to 17.2R3; 17.2X75 versions prior to 17.2X75-D105; 17.3 versions prior to 17.3R3-S2; 17.4 versions prior to 17.4R1-S7, 17.4R2-S2, 17.4R3; 18.1 versions prior to 18.1R3-S2; 18.2 versions prior to 18.2R2; 18.2X75 versions prior to 18.2X75-D12, 18.2X75-D30; 18.3 versions prior to 18.3R1-S4, 18.3R2. Junos OS releases prior to 16.1R1 are not affected.
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Analysis
by VulDB Data Team • 10/24/2023
This vulnerability exists within Juniper Networks Junos OS routing platforms where the Border Gateway Protocol (BGP) graceful restart helper mode is enabled by default. The flaw manifests when specific sequences of BGP session restart operations occur between a local device and a remote peer that also has graceful restart enabled. The technical implementation involves the routing protocol daemon (RPD) process failing to properly handle certain BGP message sequences during graceful restart operations, leading to process termination and automatic restart. This represents a critical reliability issue that can cascade into sustained service disruption.
The underlying technical flaw stems from improper state management and message processing within the RPD component when handling BGP graceful restart notifications. When a remote BGP peer initiates a graceful restart sequence, the local device's RPD process fails to maintain proper session state tracking, resulting in memory corruption or invalid pointer dereference conditions that cause the process to crash. This vulnerability operates at the protocol level and specifically affects the BGP implementation within Junos OS, making it particularly dangerous for network infrastructure devices that rely heavily on BGP for routing decisions.
The operational impact of CVE-2019-0049 extends beyond simple service interruption to create prolonged denial of service conditions that can severely impact network availability. The repeated crashes of the RPD process mean that network routing stability becomes compromised, potentially causing routing flapping, increased convergence times, and loss of connectivity between network segments. Network administrators face the challenge of maintaining routing stability while the process continuously restarts, leading to potential cascading failures in large-scale deployments where multiple routing peers are involved.
Network security practitioners should consider this vulnerability in the context of the ATT&CK framework's privilege escalation and denial of service tactics, as it can be exploited to create persistent availability issues that may require manual intervention to resolve. The vulnerability's default enabling of graceful restart helper mode means that many Juniper devices in production environments are potentially exposed without explicit configuration changes. Organizations should implement immediate mitigations including disabling graceful restart helper mode where not required, applying the relevant security patches, and monitoring for RPD process restart events in their network monitoring systems.
The vulnerability aligns with CWE-248, which addresses "Uncaught Exception" conditions in software implementations, as the RPD process does not properly handle exceptional BGP session states during graceful restart operations. Organizations should also consider the broader implications for network resilience and implement proper monitoring for process restart patterns, as this vulnerability can be triggered through legitimate BGP operations rather than malicious attack vectors. The affected versions span multiple Junos OS release lines, indicating this represents a systemic issue in the BGP implementation rather than a localized bug, requiring comprehensive patch management across all impacted systems.
Security teams should also evaluate their incident response procedures to ensure they can quickly identify and remediate RPD process crashes related to this vulnerability, as the symptoms may be indistinguishable from other network issues without proper monitoring. The default enablement of the vulnerable feature means that many organizations may not be aware of their exposure until a DoS event occurs, making proactive patch management essential for maintaining network stability and security posture.