SB2026012059 - Improper locking in Juniper Junos OS
Published: January 20, 2026
Security Bulletin ID
SB2026012059
Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Improper locking (CVE-ID: CVE-2026-21914)
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 update from vendor's website.