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Ucm6202 FirmwareOperating system · Grandstream

CVE-2020-5757

CRITICAL · 9.8 CVSS v3.1 Published 2020-07-17
Fix available
A fix is available. Upgrade to after 1.0.20.23 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
Grandstream UCM6200 series firmware version 1.0.20.23 and below is vulnerable to OS command injection via HTTP. An authenticated remote attacker can bypass command injection mitigations and execute commands as the root user by sending a crafted HTTP POST to the UCM's "New" HTTPS API.

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 Grandstream UCM6200 series IP PBX firmware versions 1.0.20.23 and below contains an OS command injection vulnerability in the 'New' HTTPS API. An authenticated attacker can bypass existing command injection mitigations via crafted HTTP POST requests, achieving root-level command execution on the device.

MitigationUpgrade the UCM6200 series firmware to version higher than 1.0.20.23. If immediate patching is not possible, restrict access to the web interface to trusted IP addresses only and change default credentials.

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
Ucm6202 FirmwareOperating system
Affected:<= 1.0.20.23
Ucm6204 FirmwareOperating system
Affected:<= 1.0.20.23
Ucm6208 FirmwareOperating system
Affected:<= 1.0.20.23

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. Identify the UCM6200 model number
    Access the device web interface and check the System Status page, or use the command line via SSH/Telnet to run 'show system info' or check the device label. Confirm the model is UCM6202, UCM6204, or UCM6208.
    Affected if The device model is NOT one of these three models.
  2. Check the installed firmware version
    In the web interface, go to System Settings > Upgrade or System Status > System Information to view the firmware version. Alternatively, access the device via SSH/Telnet and run 'cat /proc/version' or check the firmware file name during upgrade. Compare this version to 1.0.20.23.
    Affected if The firmware version is 1.0.20.23 or lower.
  3. Verify if the web interface is accessible over HTTPS
    Attempt to access the device IP address on port 443 (HTTPS) from a browser. Confirm the 'New' HTTPS API endpoint is reachable by testing a basic authenticated request to the API.
    Affected if The web interface and HTTPS API are exposed and reachable.
  4. Confirm authentication is possible
    Attempt to log in to the web interface using the default credentials (admin:admin is the factory default) or verify if any valid user account exists on the system.
    Affected if Default credentials have not been changed or any valid administrative account exists.

You are affected if you have a UCM6202, UCM6204, or UCM6208 device running firmware version 1.0.20.23 or lower with the web interface accessible and a valid login.

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 a release after 1.0.20.23
Interim mitigation

Upgrade the UCM6200 series firmware to version higher than 1.0.20.23. If immediate patching is not possible, restrict access to the web interface to trusted IP addresses only and change default credentials.

Recommended fix Moderate confidence

Grandstream UCM6200 series firmware 1.0.20.24 or later (verify latest version from official Grandstream support)

  1. 1. Access the Grandstream UCM6200 series device web interface using administrative credentials.
  2. 2. Navigate to the firmware upgrade section (typically under System Settings > Firmware Upgrade or Maintenance > Upgrade).
  3. 3. Download the latest firmware version from the official Grandstream website (www.grandstream.com).
  4. 4. Upload and apply the firmware update to the device.
  5. 5. After the upgrade completes, verify the new firmware version is installed and the device is functioning normally.
  6. 6. Review the device's security settings and ensure the HTTP/HTTPS API access controls are properly configured.
Caveat Firmware upgrades may temporarily interrupt service; backup configuration before upgrading; ensure compatibility with any integrated systems

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

Fix this in Ucm6202 Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,580
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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-2020-5757 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
  • No spam, self-promotion, credentials, or personal data