#VU121664 Double free in Juniper Junos OS - CVE-2026-21918

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Main Vulnerability Database Vulnerabilities #VU121664

#VU121664 Double free in Juniper Junos OS - CVE-2026-21918

Published: January 19, 2026


Vulnerability identifier: #VU121664
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-2026-21918
CWE-ID: CWE-415
Exploitation vector: Remote access
Exploit availability: No public exploit available
Vulnerable software:
Juniper Junos OS
Software vendor:
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 double free error in the flow processing daemon (flowd). A remote non-authenticated attacker can 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.


Remediation

Install updates from vendor's website.

External links