CVE-2025-52949 is a vulnerability identified in Juniper Networks Junos OS and Junos OS Evolved affecting the routing protocol daemon (rpd), specifically when configured for Ethernet Virtual Private Networking (EVPN) signaling. The vulnerability arises from improper handling of length parameter inconsistencies in BGP packets, classified under CWE-130. A logically adjacent BGP peer can send a specially crafted malformed BGP packet that triggers a crash and restart of the rpd process, causing a Denial of Service (DoS). This vulnerability impacts both iBGP and eBGP sessions and affects IPv4 and IPv6 protocols. The affected Junos OS versions include all releases before 21.4R3-S11, and various subsequent versions up to 24.4R2, as well as corresponding versions of Junos OS Evolved. The vulnerability does not require authentication or user interaction and has a CVSS 3.1 base score of 6.5, indicating a medium severity level. The attack vector is adjacent network (AV:A), meaning the attacker must be logically adjacent to the target device, typically within the same routing domain or network segment. The vulnerability impacts availability only, with no confidentiality or integrity impact. No known exploits are currently reported in the wild. The root cause is the failure to properly validate or handle length parameters in BGP packets, leading to inconsistent processing and a crash of the routing daemon. This sustained DoS condition can disrupt network routing and connectivity for affected devices, potentially impacting network stability and service availability.

For European organizations, especially those operating large-scale networks or service provider infrastructures relying on Juniper Networks Junos OS for routing and EVPN services, this vulnerability poses a significant risk to network availability. A successful exploitation could lead to repeated crashes of the routing daemon, causing intermittent or sustained network outages. This can disrupt critical business operations, including data center interconnects, cloud services, and enterprise WAN connectivity. The impact is particularly severe for organizations with high dependency on BGP for routing and EVPN for virtualized network overlays, such as telecommunications providers, financial institutions, and large enterprises with complex network topologies. Network outages could lead to loss of productivity, financial losses, and reputational damage. Additionally, the requirement for the attacker to be a logically adjacent BGP peer limits the attack surface but does not eliminate risk, as compromised internal systems or malicious insiders could exploit this vulnerability. The lack of confidentiality or integrity impact reduces the risk of data breaches but does not mitigate the operational disruption caused by DoS.

To mitigate this vulnerability, European organizations should prioritize upgrading affected Junos OS and Junos OS Evolved devices to the fixed versions as specified by Juniper Networks. Network administrators should: 1) Identify all devices running vulnerable Junos OS versions with EVPN signaling enabled. 2) Schedule and apply vendor-released patches or upgrades to versions beyond the fixed releases (e.g., 21.4R3-S11 or later). 3) Implement strict BGP session controls, including filtering and validating BGP peers to ensure only trusted and authenticated peers can establish sessions, reducing the risk of malicious adjacent peers. 4) Monitor BGP session stability and rpd process health to detect anomalous crashes or restarts promptly. 5) Employ network segmentation to limit the exposure of BGP peers and EVPN signaling to only necessary network segments, minimizing the attack surface. 6) Use logging and alerting mechanisms to detect malformed BGP packets or unusual traffic patterns indicative of exploitation attempts. 7) Consider deploying redundancy and failover mechanisms to maintain network availability during potential DoS events. These measures, combined with timely patching, will reduce the likelihood and impact of exploitation.