CVE-2026-21914: Juniper Junos

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

An Improper Locking vulnerability in the GTP plugin of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos). If an SRX Series device receives a specifically malformed GPRS Tunnelling Protocol (GTP) Modify Bearer Request message, a lock is acquired and never released. This results in other threads not being able to acquire a lock themselves, causing a watchdog timeout leading to FPC crash and restart. This issue leads to a complete traffic outage until the device has automatically recovered. This issue affects Junos OS on SRX Series: * all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2-S6, * 24.2 versions before 24.2R2-S3, * 24.4 versions before 24.4R2-S2, * 25.2 versions before 25.2R1-S1, 25.2R2.

Affected products

• Juniper Junos: before 22.4 (fixed in 22.4); version 22.4 only; version 23.2 only; version 23.4 only; version 24.2 only; version 24.4 only; …

Published 2026-01-15. Last modified 2026-06-17.