Out-of-bounds write in Junos OS - CVE-2026-57021
Published: July 8, 2026
Vulnerability identifier: #VU137152
CSH Severity: Medium
CVSS v4.0: 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/E:U/U:Green
CVE-ID: CVE-2026-57021
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Juniper Networks, Inc.
Affected software:
Junos OS
Junos OS
Detailed vulnerability description
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.
How to mitigate CVE-2026-57021
Install security update from vendor's website.