CVE-2025-52981 is a high-severity vulnerability identified in the flow processing daemon (flowd) component of Juniper Networks Junos OS, specifically affecting SRX1600, SRX2300, SRX 4000 Series, and SRX5000 Series with SPC3 hardware platforms. The vulnerability arises from an improper check for unusual or exceptional conditions (CWE-754) within the flowd process. An unauthenticated attacker can exploit this flaw remotely by sending a crafted sequence of Protocol Independent Multicast (PIM) packets to the affected device. This triggers a crash of the flowd daemon, leading to its restart and causing a Denial-of-Service (DoS) condition. The impact is limited to availability, as confidentiality and integrity are not affected. The vulnerability affects multiple versions of Junos OS prior to patched releases: all versions before 21.2R3-S9, 21.4 versions before 21.4R3-S11, 22.2 versions before 22.2R3-S7, 22.4 versions before 22.4R3-S6, 23.2 versions before 23.2R2-S4, 23.4 versions before 23.4R2-S4, and 24.2 versions before 24.2R2. The vulnerability does not require any authentication or user interaction, and the attack vector is network-based, making exploitation relatively straightforward if the attacker can reach the vulnerable device's network interface. This issue is distinct but related to a previously reported vulnerability CVE-2024-47503. No known exploits are currently reported in the wild, but the high CVSS score of 7.5 reflects the potential impact and ease of exploitation. Juniper Networks has not yet published official patches or mitigation details at the time of this report.

For European organizations, this vulnerability poses a significant risk to network infrastructure availability, especially for those relying on Juniper SRX series firewalls and routers for perimeter security and traffic management. A successful DoS attack could disrupt critical business operations, degrade network performance, and potentially cause outages in enterprise, government, and service provider environments. Given that Juniper SRX devices are widely deployed in Europe for their robust security features, the vulnerability could affect sectors such as finance, telecommunications, public administration, and critical infrastructure. The lack of authentication requirement and network-based attack vector means that attackers could exploit this vulnerability remotely without insider access, increasing the threat surface. Additionally, the flowd daemon crash and restart may temporarily interrupt firewall stateful inspection and traffic flow monitoring, potentially exposing networks to further risks during the downtime. Organizations with high availability requirements and those operating in regulated industries may face compliance and operational challenges if this vulnerability is exploited.

1. Immediate deployment of Juniper-released patches or updates as soon as they become available is critical. Organizations should monitor Juniper's advisories closely. 2. In the interim, restrict network access to the management and data plane interfaces of affected SRX devices, especially blocking or filtering PIM protocol traffic from untrusted sources to reduce exposure. 3. Implement network segmentation and strict ingress filtering to limit exposure of vulnerable devices to potentially malicious external traffic. 4. Enable and monitor detailed logging on SRX devices to detect unusual PIM packet sequences or flowd crashes, facilitating early detection of exploitation attempts. 5. Consider deploying redundant firewall clusters or failover mechanisms to maintain availability in case of flowd daemon crashes. 6. Conduct regular vulnerability assessments and penetration testing focused on network device resilience to DoS attacks. 7. Review and update incident response plans to include scenarios involving network device DoS and ensure rapid recovery procedures are in place. 8. Engage with Juniper support for guidance and to obtain any available workarounds or hotfixes prior to official patch releases.