#VU121697 Improper locking in Juniper Junos OS - CVE-2026-21914
Published: January 20, 2026
Vulnerability identifier: #VU121697
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-21914
CWE-ID: CWE-667
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Juniper Junos OS
Juniper Junos OS
Software vendor:
Juniper Networks, Inc.
Juniper Networks, Inc.
Description
The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to improper locking error in the GTP plugin. A remote non-authenticated attacker can 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.
Remediation
Install updates from vendor's website.