CVE-2025-52964 is a Reachable Assertion vulnerability (CWE-617) found in the Routing Protocol Daemon (rpd) component of Juniper Networks Junos OS and Junos OS Evolved. This vulnerability allows an unauthenticated attacker with network access to cause a Denial of Service (DoS) condition by sending a specially crafted BGP UPDATE packet. The vulnerability is triggered only when BGP multipath with the "pause-computation-during-churn" feature is enabled on the device. Upon receiving the malicious BGP UPDATE, the rpd process crashes and restarts, and continuous exploitation leads to sustained DoS, disrupting routing functionality. The attacker must be an established BGP peer to send the malicious packet, which limits the attack vector to network-level access with BGP session privileges. The affected Junos OS versions include all releases before 21.4R3-S7, and certain versions from 22.3, 22.4, 23.2, and 23.4 prior to their respective patch releases. Similarly, Junos OS Evolved versions before 21.4R3-S7-EVO and corresponding versions in 22.3, 22.4, 23.2, and 23.4 are vulnerable. The CVSS v3.1 base score is 6.5 (medium severity), reflecting the attack vector as adjacent network (AV:A), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no impact on confidentiality or integrity (C:N/I:N), but high impact on availability (A:H). No known exploits are currently reported in the wild. This vulnerability can disrupt network routing services, potentially causing outages or degraded network performance in environments relying on Juniper routing devices with the affected software and configuration.

For European organizations, this vulnerability poses a significant risk to network infrastructure stability, particularly for ISPs, data centers, cloud providers, and large enterprises that rely on Juniper routers for BGP routing. A successful exploitation can cause routing daemon crashes leading to temporary loss of routing capabilities, network outages, or degraded service availability. This can impact critical services, including internet connectivity, inter-office communications, and cloud service delivery. Given the reliance on BGP for internet routing, disruption could cascade to affect multiple downstream networks. The requirement for an established BGP session limits the attack surface to trusted peers or compromised BGP neighbors, but insider threats or misconfigured BGP peers could be leveraged by attackers. European organizations operating in sectors with high availability requirements, such as finance, telecommunications, and government, may face operational disruptions and potential regulatory scrutiny if network outages occur. Additionally, the vulnerability could be exploited as part of a broader attack campaign targeting network infrastructure to cause denial of service or to facilitate further attacks by disrupting network stability.

1. Immediate patching: Organizations should upgrade Junos OS and Junos OS Evolved to the fixed versions listed by Juniper (e.g., 21.4R3-S7 or later) as soon as possible to eliminate the vulnerability. 2. Configuration review: Disable BGP multipath with the "pause-computation-during-churn" feature if it is not essential, as this configuration is required to trigger the vulnerability. 3. BGP peer security: Restrict BGP peering to trusted and authenticated peers only, using strong authentication mechanisms such as TCP MD5 signatures or TCP-AO to prevent unauthorized BGP session establishment. 4. Network segmentation: Isolate BGP routers from untrusted networks and limit access to BGP sessions to reduce the risk of malicious BGP UPDATE injection. 5. Monitoring and alerting: Implement monitoring on rpd process stability and BGP session anomalies to detect potential exploitation attempts early. 6. Incident response readiness: Prepare response plans for potential DoS events impacting routing to minimize downtime and impact. 7. Vendor advisories: Stay updated with Juniper security advisories for any new patches or mitigations related to this vulnerability.