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JunosOperating system · Juniper

CVE-2026-57021

MEDIUM · 5.3 CVSS v3.1 Published 2026-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

An out-of-bounds write vulnerability in the http-gatekeeper (http-gk) process of Juniper Junos OS on SRX Series devices allows an unauthenticated, network-based attacker to crash the http-gk process by sending specially formatted requests when the device is configured for remote-access VPN with pre-logon compliance check. This crash disrupts J-Web, remote access VPN, and firewall authentication services until the process automatically restarts.

MitigationApply the vendor-supplied Junos OS patches for the listed affected versions (23.2R2-S7 and later, 23.4R2-S8 and later, 24.2R2-S4 and later, 24.4R2-S4 and later, 25.2R2 and later, 25.4R1-S1/25.4R2 and later). Alternatively, if patching is not immediately feasible, consider disabling pre-logon compliance check for remote-access VPN as a temporary mitigation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
JunosOperating system
Affected:= 23.2= 23.4= 24.2= 24.4= 25.2= 25.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm device is an SRX Series platform
    Run 'show chassis hardware' or 'show system information' to identify the device model
    Affected if Device is NOT an SRX Series device (vulnerability only affects SRX Series)
  2. Check Junos OS version
    Run 'show version' to obtain the installed Junos OS version
    Affected if Version is 23.2, 23.4, 24.2, 24.4, 25.2, or 25.4 (any build within these release trains)
  3. Verify remote-access VPN configuration exists
    Run 'show configuration | match remote-access' or check vpn configuration under 'access' or 'security' hierarchy
    Affected if No remote-access VPN is configured (vulnerability requires this configuration)
  4. Check if pre-logon compliance check is enabled
    Run 'show configuration | match pre-logon' or examine the remote-access VPN profile for compliance check settings under 'access profile' or 'user firewall' configuration
    Affected if Pre-logon compliance check IS enabled - this is the critical condition required for the vulnerability to be exploitable
  5. Confirm http-gk process is running
    Run 'show system processes http-gk' or 'ps aux | grep http-gk' to verify the process is active
    Affected if http-gk process is running and exposed to network requests

A user is affected if they are running Junos OS versions 23.2, 23.4, 24.2, 24.4, 25.2, or 25.4 on an SRX Series device with remote-access VPN configured AND pre-logon compliance check enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-supplied Junos OS patches for the listed affected versions (23.2R2-S7 and later, 23.4R2-S8 and later, 24.2R2-S4 and later, 24.4R2-S4 and later, 25.2R2 and later, 25.4R1-S1/25.4R2 and later). Alternatively, if patching is not immediately feasible, consider disabling pre-logon compliance check for remote-access VPN as a temporary mitigation.

Recommended fix High confidence

23.2R2-S7 / 23.4R2-S8 / 24.2R2-S4 / 24.4R2-S4 / 25.2R2 / 25.4R2 (depending on current branch)

  1. 1. Identify the current Junos OS version on the SRX Series device using 'show version'
  2. 2. If running 23.2, upgrade to 23.2R2-S7 or later
  3. 3. If running 23.4, upgrade to 23.4R2-S8 or later
  4. 4. If running 24.2, upgrade to 24.2R2-S4 or later
  5. 5. If running 24.4, upgrade to 24.4R2-S4 or later
  6. 6. If running 25.2, upgrade to 25.2R2 or later
  7. 7. If running 25.4, upgrade to 25.4R1-S1, 25.4R2, or later
  8. 8. After upgrade, verify the http-gk process is running using 'show system processes | match http-gk'
Caveat Standard Junos upgrade procedures apply; always review release notes for known issues and test in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,980
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-57021 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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