This vulnerability arises from a missing synchronization mechanism in the flow collector handler of Junos OS Evolved on QFX Series devices. When the reachability status of an sFlow collector changes, the system updates the corresponding next-hop entry. If this update occurs concurrently with the sFlow thread accessing the next-hop data, it causes the evo-pfemand process to crash. This crash results in a Denial-of-Service condition affecting all traffic forwarding until the process restarts automatically. The issue can be triggered by an adjacent, unauthenticated attacker. A fix is available in versions 23.4R2-S7-EVO and later for 23.4, 24.2R2-S5-EVO and later for 24.2, 24.4R2-S3-EVO and later for 24.4, and 25.2R2-EVO and later for 25.2. The vendor manages remediation for this cloud-hosted service.

An unauthenticated attacker with adjacent network access can cause the evo-pfemand process to crash, resulting in a Denial-of-Service that disrupts all traffic forwarding on affected Junos OS Evolved QFX Series devices until the process restarts automatically. There is no impact on confidentiality or integrity.

The vendor manages remediation for this cloud-hosted service. Users should ensure their Junos OS Evolved on QFX Series devices are updated to the fixed versions: 23.4R2-S7-EVO or later for 23.4, 24.2R2-S5-EVO or later for 24.2, 24.4R2-S3-EVO or later for 24.4, and 25.2R2-EVO or later for 25.2. Patch status is confirmed as available. No additional mitigation steps are indicated by the vendor advisory.