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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 17 Nov 2023.
JunosOperating system · Juniper

CVE-2023-36846

MEDIUM · 5.3 CVSS v3.1 Published 2023-08-17
Fix available
A fix is available. Upgrade to 20.4 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Remotely reachable No privileges Zero-click

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
A Missing Authentication for Critical Function vulnerability in Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause limited impact to the file system integrity. With a specific request to user.php that doesn't require authentication an attacker is able to upload arbitrary files via J-Web, leading to a loss of integrity for a certain  part of the file system, which may allow chaining to other vulnerabilities. This issue affects Juniper Networks Junos OS on SRX Series: * All versions prior to 20.4R3-S8; * 21.1 versions 21.1R1 and later; * 21.2 versions prior to 21.2R3-S6; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3-S5; * 22.1 versions prior to 22.1R3-S3; * 22.2 versions prior to 22.2R3-S2; * 22.3 versions prior to 22.3R2-S2, 22.3R3; * 22.4 versions prior to 22.4R2-S1, 22.4R3.

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

Missing authentication in J-Web user.php endpoint on Juniper SRX Series allows unauthenticated remote attackers to upload arbitrary files to the file system. This provides an initial foothold that can be chained with other vulnerabilities for further exploitation.

MitigationUpgrade Junos OS to the specified patched versions. As an interim measure, disable or restrict access to the J-Web interface from untrusted networks.

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:< 20.4= 20.4= 21.1= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4

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
Low
Availability
None

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

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. Verify J-Web interface is enabled
    Run 'show system services web-management' or check configuration for 'system services web-management'
    Affected if J-Web is enabled and the device is reachable over HTTP/HTTPS on the management interface
  2. Confirm Junos OS version
    Run 'show version' or 'show version detail' to obtain the installed Junos version
    Affected if The installed version matches < 20.4, = 20.4, = 21.1, = 21.2, = 21.3, = 21.4, = 22.1, = 22.2, = 22.3, or = 22.4
  3. Check for exposure of J-Web to untrusted networks
    Review the web-management configuration and firewall policies to determine if J-Web is accessible from outside trusted management networks
    Affected if J-Web is exposed to the internet or untrusted networks without IP-based access restrictions
  4. Inspect J-Web PHP endpoint accessibility
    Attempt to access /esp/pfc/user.php or verify the endpoint exists in the web container (note: only perform authorized penetration testing or with explicit permission)
    Affected if The user.php endpoint responds without requiring authentication

The device is affected if J-Web is enabled, the Junos version falls within the listed affected versions, and the J-Web interface is accessible to unauthenticated attackers.

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
Upgrade available Upgrade to 20.4 or later
Fixed in 20.4
Interim mitigation

Upgrade Junos OS to the specified patched versions. As an interim measure, disable or restrict access to the J-Web interface from untrusted networks.

Recommended fix High confidence

20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S5, 22.1R3-S3, 22.2R3-S2, 22.3R3, or 22.4R3 (depending on current branch)

  1. 1. Identify the current Junos OS version on the SRX device using 'show version' command
  2. 2. Determine the appropriate fixed release based on the current version branch (see upgrade_path)
  3. 3. Backup the current configuration using 'request system configuration archive save' or export config to external storage
  4. 4. Download the appropriate Junos upgrade image from Juniper Networks support portal
  5. 5. Upgrade the device using 'request system software add <package-name>' command
  6. 6. Reboot the device after upgrade completes using 'request system reboot'
  7. 7. Verify the device is running the fixed version with 'show version'
  8. 8. Confirm J-Web PHP access now properly requires authentication
Caveat Major version upgrades (e.g., 20.x to 21.x, 21.x to 22.x) may introduce compatibility changes - review Juniper release notes for breaking changes and feature modifications before upgrading

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

Fix this in Junos Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,080.

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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-2023-36846 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data