Medium · published October 14, 2026
An Improper Resource Locking vulnerability in the UTM processing of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).
When UTM WebFiltering is configured and the WebFiltering cloud server is unreachable, sustained HTTP traffic load may cause the UTM subsystem to crash and restart, which will lead to a complete service outage until the system has recovered.
When category lookup requests cannot be completed, they accumulate internally. Under high load and specific timing conditions, an invalid internal state can occur during cleanup of pending WebFiltering lookups, resulting in a crash of the UTM process.
This issue applies to both NextGeneration WebFiltering (NGWF) and Enhanced WebFiltering (EWF).
This issue affects Junos OS on SRX Series:
* 23.2 versions from 23.2R2 before 23.2R2-S7.7;
* 23.4 versions from 23.4R2 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-S3, 25.4R2.