CVE-2026-57023 Juniper Networks CVE debrief

Who should care

Users of Juniper Networks Junos OS on MX Series with SPC3, and SRX Series should apply patches to prevent Denial of Service (DoS) attacks. This vulnerability has a CVSS score of 8.7 and is considered HIGH severity. Affected operators, platforms, vulnerability-management, and security teams should prioritize patching and review compensating controls for exposed systems.

Technical summary

The vulnerability exists in the TCP proxy plugin of Juniper Networks Junos OS on MX Series with SPC3, and SRX Series. A TCP packet with a specifically malformed TCP header can cause the flow processing daemon (flowd) to crash and restart, resulting in a complete service outage until the system automatically recovers. This issue affects Junos OS versions 23.4 before 23.4R2-S7, 24.2 before 24.2R2-S4, 24.4 before 24.4R2-S3, and 25.2 before 25.2R2. Users should review system logs for flowd crashes and monitor for potential Denial of Service (DoS) attacks.

Defensive priority

High priority should be given to patching Juniper Networks Junos OS on MX Series with SPC3, and SRX Series to prevent potential Denial of Service (DoS) attacks. Defenders should verify system logs for flowd crashes and monitor for potential attacks. Compensating controls, such as restricting network access to TCP proxy plugin and monitoring system logs, should be reviewed and implemented if necessary. Asset inventory and rollback/change windows should also be considered to minimize potential impact. Source tracking and exposure review are recommended to ensure comprehensive understanding of the vulnerability. Monitoring and detection capabilities should be reviewed to ensure they can identify potential attacks. Rollback and change management processes should be updated to reflect the urgency of patching this vulnerability. Vulnerability management and security teams should track exceptions and retest remediated assets to ensure the vulnerability is properly addressed. The CVE record and official advisory should be reviewed to validate affected scope, severity, and vendor guidance. Managed environments should be assessed for affected product deployments, and owners should be assigned for follow-up. The impact of the vulnerability on the organization should be assessed, and a plan should be developed to address potential Denial of Service (DoS) attacks. The plan should include applying patches, reviewing compensating controls, and monitoring system logs. The plan should be implemented through normal change control processes, and exceptions should be tracked and addressed. The vulnerability should be prioritized based on its CVSS score and potential impact on the organization. The organization should also consider implementing additional security controls, such as network segmentation and access controls, to minimize the potential impact of a successful attack. The organization should review and update its incident response plan to ensure it can respond effectively to a potential Denial of Service (DoS) attack. The organization should also consider providing additional training to security teams and operators on the vulnerability and its potential impact. The CVE-

Recommended defensive actions

• Apply patches for affected Junos OS versions: 23.4R2-S7, 24.2R2-S4, 24.4R2-S3, and 25.2R2
• Restrict network access to TCP proxy plugin
• Monitor system logs for flowd crashes
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Review compensating controls for exposed systems while remediation is scheduled and verified.

Evidence notes

The CVE record was published on 2026-07-09T22:17:07.397Z and was last modified on 2026-07-10T16:16:35.447Z. The NVD entry is currently Received. Limited details are available about the vulnerability, and additional information may be necessary for a comprehensive understanding. Evidence is limited, and defenders should verify system logs for flowd crashes and monitor for potential Denial of Service (DoS) attacks.

Official resources