CVE-2026-57021: CWE-787 Out-of-bounds Write in Juniper Networks Junos OS
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.
AI Analysis
Technical Summary
CVE-2026-57021 is an out-of-bounds write vulnerability (CWE-787) in the http-gatekeeper (http-gk) component of Juniper Networks Junos OS on SRX Series devices. When remote-access VPN with pre-logon compliance check is enabled, an unauthenticated attacker can send specially crafted network requests that trigger an out-of-bounds write, causing the http-gk process to crash. This crash leads to denial of service for all services dependent on the system services web-management configuration until the process automatically restarts. The vulnerability affects Junos OS versions 23.2 before 23.2R2-S7, 23.4 before 23.4R2-S8, 24.2 before 24.2R2-S4, 24.4 before 24.4R2-S4, 25.2 before 25.2R2, and 25.4 before 25.4R1-S1 and 25.4R2.
Potential Impact
Successful exploitation results in denial of service by crashing the http-gk process, causing unavailability of services relying on system services web-management such as J-Web, remote access VPN, and firewall authentication. The process automatically restarts, so the denial of service is temporary but can disrupt network operations and management access.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch information is provided in the available data. Until a patch is available, consider disabling remote-access VPN pre-logon compliance check if feasible or applying vendor-recommended mitigations once published.
CVE-2026-57021: CWE-787 Out-of-bounds Write in Juniper Networks Junos OS
Description
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.
CVSS v3.1
Score 5.3medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-57021 is an out-of-bounds write vulnerability (CWE-787) in the http-gatekeeper (http-gk) component of Juniper Networks Junos OS on SRX Series devices. When remote-access VPN with pre-logon compliance check is enabled, an unauthenticated attacker can send specially crafted network requests that trigger an out-of-bounds write, causing the http-gk process to crash. This crash leads to denial of service for all services dependent on the system services web-management configuration until the process automatically restarts. The vulnerability affects Junos OS versions 23.2 before 23.2R2-S7, 23.4 before 23.4R2-S8, 24.2 before 24.2R2-S4, 24.4 before 24.4R2-S4, 25.2 before 25.2R2, and 25.4 before 25.4R1-S1 and 25.4R2.
Potential Impact
Successful exploitation results in denial of service by crashing the http-gk process, causing unavailability of services relying on system services web-management such as J-Web, remote access VPN, and firewall authentication. The process automatically restarts, so the denial of service is temporary but can disrupt network operations and management access.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch information is provided in the available data. Until a patch is available, consider disabling remote-access VPN pre-logon compliance check if feasible or applying vendor-recommended mitigations once published.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- juniper
- Date Reserved
- 2026-06-23T16:27:00.248Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a50171668715ace431ea1f0
Added to database: 07/09/2026, 21:48:06 UTC
Last enriched: 07/17/2026, 09:54:21 UTC
Last updated: 08/23/2026, 22:52:12 UTC
Views: 84
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