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Edgemax FirmwareOperating system · Ui

CVE-2020-8234

CRITICAL · 9.8 CVSS v3.1 Published 2020-08-21
Fix available
A fix is available. Upgrade to 1.9.1 or later.
See remediation →
100/100
Remediation priority · Urgent
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 vulnerability exists in The EdgeMax EdgeSwitch firmware <v1.9.1 where the EdgeSwitch legacy web interface SIDSSL cookie for admin can be guessed, enabling the attacker to obtain high privileges and get a root shell by a Command injection.

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

The EdgeSwitch legacy web interface uses a guessable SIDSSL session cookie for admin authentication. An attacker can predict or brute-force this cookie value to hijack an admin session, then exploit a command injection vulnerability to gain root shell access on the device.

MitigationUpgrade EdgeSwitch firmware to v1.9.1 or later. If immediate patching is not possible, restrict network access to the management interface and monitor for suspicious authentication patterns.

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
Edgemax FirmwareOperating system
Affected:< 1.9.1

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
High
Integrity
High
Availability
High

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

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. Check Edgemax firmware version
    Access the device console or use SNMP/SSH to retrieve the firmware version. On the EdgeSwitch CLI, run 'show version' or check the web interface login page footer for the version number.
    Affected if The firmware version is below 1.9.1 (e.g., 1.8.x, 1.7.x, etc.)
  2. Identify legacy web interface exposure
    Attempt to access the device's web interface on port 443/HTTPS. The legacy interface typically responds with a login page at the root path. Check if it returns a session cookie named 'SIDSSL' or similar session identifier.
    Affected if The legacy web interface is accessible and uses a session cookie that appears predictable or static across logins
  3. Verify management interface accessibility
    Determine if the web management interface is listening on externally accessible IPs or is reachable from untrusted networks. Check firewall rules, ACLs, or interface bindings.
    Affected if The management interface is exposed to the internet or untrusted LAN segments without restrictive ACLs
  4. Check for predictable session cookies
    Attempt multiple login attempts from different client IPs and observe the SIDSSL cookie value. Look for patterns such as sequential values, low entropy, or predictable generation.
    Affected if The SIDSSL cookie value can be predicted, brute-forced, or shows low entropy (e.g., simple incrementing values)
  5. Inspect for command injection access path
    After obtaining a valid session cookie, check if there are web interface features that allow executing system commands or if there are known vulnerable endpoints.
    Affected if The web interface provides any system command execution functionality accessible to authenticated admin users

You are affected if your EdgeSwitch/Edgemax device runs firmware below version 1.9.1 and has the legacy web interface with the SIDSSL cookie exposed to untrusted networks.

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 1.9.1 or later
Fixed in 1.9.1
Interim mitigation

Upgrade EdgeSwitch firmware to v1.9.1 or later. If immediate patching is not possible, restrict network access to the management interface and monitor for suspicious authentication patterns.

Recommended fix High confidence

EdgeSwitch firmware v1.9.1 or later

  1. 1. Backup current EdgeSwitch configuration before proceeding with firmware upgrade
  2. 2. Download EdgeSwitch firmware version 1.9.1 or later from the official Ubiquiti Networks support portal (www.ui.com)
  3. 3. Access the EdgeSwitch management interface using a secure connection
  4. 4. Navigate to the System or Maintenance section in the web GUI
  5. 5. Select the firmware file downloaded in step 2
  6. 6. Initiate the firmware upgrade and wait for completion
  7. 7. Verify the upgrade was successful by checking the firmware version in the device status
  8. 8. Confirm that the SIDSSL cookie behavior has been fixed by logging in and verifying session management
Caveat Review Ubiquiti release notes for v1.9.1 to check for any configuration or feature changes that may require adjustment

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

Fix this in Edgemax Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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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-2020-8234 in production — separate from our analysis above.

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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
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