The vulnerability is an Improper Resource Locking flaw in the UTM processing of Junos OS on SRX Series. When UTM WebFiltering is enabled and the cloud server cannot be reached, a sustained HTTP traffic load allows an unauthenticated, network‑based attacker to cause the UTM subsystem to crash and restart. This results in a complete service outage until the device recovers, effectively a denial‑of‑service.

Affected are Juniper Networks Junos OS installations on SRX Series running the following releases: 23.2R2 before 23.2R2‑S7.7; 23.4R2 before 23.4R2‑S8.13; 24.2 before 24.2R2‑S5.5; 24.4 before 24.4R2‑S4; 25.2 before 25.2R2‑S1; and 25.4 before 25.4R1‑S3 or 25.4R2. Devices updated to 23.2R2‑S7.7, 23.4R2‑S8.13, 24.2R2‑S5.5, 24.4R2‑S4, 25.2R2‑S1, 25.4R1‑S3, 25.4R2*, 26.2R1, or any later release contain the fix and are not affected.

The CVSS score of 8.2 indicates high severity, and the EPSS score of <1% (0.00313) indicates a very low but non‑zero exploitation probability. The flaw is not listed in the CISA KEV catalog. Exploitation requires only network connectivity and does not demand authentication; an attacker can flood the device with HTTP requests while WebFiltering is configured and the cloud endpoint is unreachable. Once the internal state becomes invalid during cleanup of pending lookups, the UTM process crashes, and the router must restart, causing downtime.