CVE-2026-57021: SRX Series: If VPN compliance-check is configured an attacker can cause http-gk process crash

Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.

Affected and fixed versions

Product / branch	Fixed in
Junos OS (SRX Series) 23.2	23.2R2-S7 or later
Junos OS (SRX Series) 23.4	23.4R2-S8 or later
Junos OS (SRX Series) 24.2	24.2R2-S4 or later
Junos OS (SRX Series) 24.4	24.4R2-S4 or later
Junos OS (SRX Series) 25.2	25.2R2 or later
Junos OS (SRX Series) 25.4	25.4R1-S1, 25.4R2 or later

Always confirm against the vendor advisory, which lists every fixed hotfix.

What it is

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.

Am I affected?

To be exposed to this issue, the device needs to be configured to perform client compliance checks with:

[ security remote-access compliance pre-logon ... ]

Workarounds

There are no known workarounds for this issue.

Exploitation

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.