Medium · published October 14, 2026
An Improper Resource Locking vulnerability in the clock synchronization daemon (clksyncd) of Juniper Networks Junos OS on MX Series allows a unauthenticated, logically adjacent attacker to cause a Denial-of-Service (DoS).
If a SyncE or PTP upstream node sends a malformed message to an MX device equipped with SCBE3, a false 19.44MHz alarm is generated on the master RE. This leads to persistent RE switchovers and a clksyncd process crash. This issue is outside the attacker's direct control as it's a race condition.
This issue affects Junos OS on MX Series:
* All versions before 23.2R2-S7.7;
* 23.4 versions before 23.4R2-S8.13;
* 24.2 versions before 24.2R2-S5.5;
* 24.4 versions before 24.4R2-S4;
* 25.2 versions before 25.2R2-S1;
* 25.4 versions before 25.4R1-S2.