CVE-2026-21914

Summary

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 Software

VendorProductVersion RangeStatus
Juniper NetworksJunos OS0 < 22.4R3-S8affected
Juniper NetworksJunos OS23.2 < 23.2R2-S5affected
Juniper NetworksJunos OS23.4 < 23.4R2-S6affected
Juniper NetworksJunos OS24.2 < 24.2R2-S3affected
Juniper NetworksJunos OS24.4 < 24.4R2-S2affected
Juniper NetworksJunos OS25.2 < 25.2R1-S1, 25.2R2affected

Weaknesses

  • CWE-667: CWE-667 Improper Locking

Workarounds

There are no known workarounds for this issue.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References