CVE-2026-21918

Summary

A Double Free vulnerability in the flow processing daemon (flowd) of Juniper Networks Junos OS on SRX and MX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). On all SRX and MX Series platforms, when during TCP session establishment a specific sequence of packets is encountered a double free happens. This causes flowd to crash and the respective FPC to restart.

This issue affects Junos OS on SRX and MX Series:

  • all versions before 22.4R3-S7,
  • 23.2 versions before 23.2R2-S3,
  • 23.4 versions before 23.4R2-S4,
  • 24.2 versions before 24.2R2.

Affected Software

VendorProductVersion RangeStatus
Juniper NetworksJunos OS0 < 22.4R3-S7affected
Juniper NetworksJunos OS23.2 < 23.2R2-S3affected
Juniper NetworksJunos OS23.4 < 23.4R2-S4affected
Juniper NetworksJunos OS24.2 < 24.2R2affected

Weaknesses

  • CWE-415: CWE-415 Double Free

Workarounds

There are no known workarounds for this issue.

ADP Enrichment

CISA ADP Vulnrichment

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

References