CVE-2026-57021: Junos OS: SRX Series: If VPN compliance-check is configured an attacker can cause http-gk process crash
An Out-of-bounds Write vulnerability in the http-gatekeeper (http-gk) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).
If an SRX Series device is configured for remote-access VPN with pre-logon compliance check, a network-based attacker sending specifically formatted requests can trigger an out of bounds write leading to an http-gk process crash. This crash leads to unavailability of all services depending on the [ system services web-management ] configuration (like J-Web, remote access VPN and firewall authentication) until the process automatically restarts.
This issue affects Junos OS on SRX Series:
23.2 versions before 23.2R2-S7, 23.4 versions before 23.4R2-S8, 24.2 versions before 24.2R2-S4, 24.4 versions before 24.4R2-S4, 25.2 versions before 25.2R2, 25.4 versions before 25.4R1-S1, 25.4R2.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Juniper Networks Junos OS (SRX Series) http-gatekeeper (http-gk)to a version that resolves this vulnerability.Fixed in 23.2R2-S7 - Upgrade
Upgrade
Juniper Networks Junos OS (SRX Series) http-gatekeeper (http-gk)to a version that resolves this vulnerability.Fixed in 23.4R2-S8 - Upgrade
Upgrade
Juniper Networks Junos OS (SRX Series) http-gatekeeper (http-gk)to a version that resolves this vulnerability.Fixed in 24.2R2-S4 - Upgrade
Upgrade
Juniper Networks Junos OS (SRX Series) http-gatekeeper (http-gk)to a version that resolves this vulnerability.Fixed in 24.4R2-S4 - Upgrade
Upgrade
Juniper Networks Junos OS (SRX Series) http-gatekeeper (http-gk)to a version that resolves this vulnerability.Fixed in 25.2R2 - Upgrade
Upgrade
Juniper Networks Junos OS (SRX Series) http-gatekeeper (http-gk)to a version that resolves this vulnerability.Fixed in 25.4R1-S1 - Upgrade
Upgrade
Juniper Networks Junos OS (SRX Series) http-gatekeeper (http-gk)to a version that resolves this vulnerability.Fixed in 25.4R2 - Upgrade
Upgrade
Juniper Networks Junos OS (SRX Series) http-gatekeeper (http-gk)to a version that resolves this vulnerability.Fixed in 26.2R1 - Compensating control
If remote-access VPN with pre-logon compliance check is configured, mitigate by removing/disable the VPN compliance-check configuration until the device is upgraded, since a network-based attacker can crash the http-gk process and cause DoS of services depending on system services web-management.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-57021?
CVE-2026-57021 has a medium severity score of 6.9.
How do I fix CVE-2026-57021?
To fix CVE-2026-57021, ensure that your Junos OS on SRX Series devices is updated to the latest version that addresses this vulnerability.
What effect does CVE-2026-57021 have on my system?
CVE-2026-57021 allows an unauthenticated attacker to cause a Denial-of-Service (DoS) by crashing the http-gatekeeper process.
Who is affected by CVE-2026-57021?
CVE-2026-57021 affects Juniper Networks Junos OS running on SRX Series devices configured for remote-access VPN with pre-logon compliance checks.
Can I exploit CVE-2026-57021 remotely?
Yes, CVE-2026-57021 can be exploited by an unauthenticated, remote-based attacker.