Use-after-free in Junos OS and Junos OS Evolved - CVE-2026-21908
Published: January 20, 2026
Vulnerability identifier: #VU121702
CSH Severity: Medium
CVSS v4: 7.5 [CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-21908
CWE-ID: CWE-416
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to execute arbitrary code.
The vulnerability exists due to a use-after-free error in the 802.1X authentication daemon (dot1xd). A remote authenticated user can execute arbitrary code with elevated privileges.
This issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.
Affected software
Junos OS
Junos OS Evolved
Junos OS Evolved
How to mitigate CVE-2026-21908
Install updates from vendor's website.
Junos OS - addressed in versions 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S1, 25.2R1-S2, 25.2R2, 25.4R1
Junos OS Evolved - addressed in versions 23.2R2-S5-EVO, 23.4R2-S6-EVO, 24.2R2-S3-EVO, 24.4R2-S1-EVO, 25.2R1-S2-EVO, 25.2R2-EVO, 25.4R1-EVO
Junos OS Evolved - addressed in versions 23.2R2-S5-EVO, 23.4R2-S6-EVO, 24.2R2-S3-EVO, 24.4R2-S1-EVO, 25.2R1-S2-EVO, 25.2R2-EVO, 25.4R1-EVO