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CVE-2026-57021

5.3 · MEDIUM

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).

Published Jul 9, 2026CWE-787EPSS 0.47%

Overview

CVE-2026-57021 is a medium-severity vulnerability. It was published on July 9, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refsupportportal.juniper.net/JSA110081

How CyberStrike helps

Frequently asked questions

What is CVE-2026-57021?

CVE-2026-57021 is a medium-severity vulnerability. It was published on July 9, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-57021?

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-57021?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-57021?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-57021 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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