Out-of-bounds write in Junos OS - CVE-2026-57021
Published: July 8, 2026
Vulnerability identifier: #VU137152
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-57021
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to out-of-bounds write in the http-gatekeeper (http-gk) process when handling specifically formatted requests. A remote attacker can send specially crafted requests to cause a denial of service.
Only devices configured for remote-access VPN with pre-logon compliance checks are vulnerable. The crash can make services depending on web-management unavailable until the process automatically restarts.
Affected software
Junos OS
How to mitigate CVE-2026-57021
Install security update from vendor's website.
Junos OS - addressed in versions 23.2R2-S7, 23.4R2-S8, 24.2R2-S4, 24.4R2-S4, 25.2R2, 25.4R1-S1, 25.4R2, 26.2R1