R8500g4 FirmwareOperating system · Zte

CVE-2020-6871

CRITICAL · 9.8 CVSS v3.1 Published 2020-07-20

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

100/100

Remediation priority · Urgent

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

The server management software module of ZTE has an authentication issue vulnerability, which allows users to skip the authentication of the server and execute some commands for high-level users. This affects: <R5300G4V03.08.0100/V03.07.0300/V03.07.0200/V03.07.0108/V03.07.0100/V03.05.0047/V03.05.0046/V03.05.0045/V03.05.0044/V03.05.0043/V03.05.0040/V03.04.0020;R8500G4V03.07.0103/V03.07.0101/V03.06.0100/V03.05.0400/V03.05.0020;R5500G4V03.08.0100/V03.07.0200/V03.07.0100/V03.06.0100>

Technical summary

dbcve analysis · high confidence

ZTE server management software contains an authentication bypass vulnerability (CVSS 9.8) allowing unauthenticated attackers to skip the authentication mechanism and execute high-privilege commands. The vulnerability affects multiple firmware versions of R5300G4, R8500G4, and R5500G4 server models. The critical severity indicates network-exploitable, low-complexity attacks with complete confidentiality and integrity impact.

MitigationApply available firmware updates from ZTE for the affected versions; if patches are unavailable, restrict network access to management interfaces using firewalls or VPN access controls to limit exposure.

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

Affected products & versions

NVD · CPE data

R8500g4 FirmwareOperating system

Affected:= 03.05.0020= 03.05.0400= 03.06.0100= 03.07.0101= 03.07.0103

R5500g4 FirmwareOperating system

Affected:= 03.06.0100= 03.07.0100= 03.07.0200= 03.08.0100

R5300g4 FirmwareOperating system

Affected:= 03.04.0020= 03.05.0040= 03.05.0043= 03.05.0044= 03.05.0045= 03.05.0046= 03.05.0047= 03.07.0100= 03.07.0108= 03.07.0200= 03.07.0300= 03.08.0100

CVSS breakdown

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?

dbcve checks

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

Identify server model

Locate the model number of the ZTE server - look for R5300G4, R8500G4, or R5500G4 label on the device chassis or in the hardware inventory

Affected if Model is R5300G4, R8500G4, or R5500G4
Check firmware version on R8500g4

Access the device management interface or use firmware version check command; compare against affected versions: 03.05.0020, 03.05.0400, 03.06.0100, 03.07.0101, 03.07.0103

Affected if Installed firmware version matches any of the listed versions for R8500g4
Check firmware version on R5500g4

Access the device management interface or use firmware version check command; compare against affected versions: 03.06.0100, 03.07.0100, 03.07.0200, 03.08.0100

Affected if Installed firmware version matches any of the listed versions for R5500g4
Check firmware version on R5300g4

Access the device management interface or use firmware version check command; compare against affected versions: 03.04.0020, 03.05.0040, 03.05.0043, 03.05.0044, 03.05.0045, 03.05.0046, 03.05.0047, 03.07.0100, 03.07.0108, 03.07.0200, 03.07.0300, 03.08.0100

Affected if Installed firmware version matches any of the listed versions for R5300g4
Verify management interface exposure

Check if the server management interface (typically web-based or SSH) is accessible from untrusted networks

Affected if Management interface is exposed to the internet or untrusted networks without firewall/VPN controls

System is affected if it is a ZTE R5300G4, R8500G4, or R5500G4 server running any of the specific firmware versions listed AND the management interface is network-accessible.

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

Remediation

dbcve · scoped

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Apply available firmware updates from ZTE for the affected versions; if patches are unavailable, restrict network access to management interfaces using firewalls or VPN access controls to limit exposure.

Recommended fix Moderate confidence

Latest firmware version available from ZTE support for R5300g4/R5500g4/R8500g4 (check support.zte.com.cn for specific version number)

1. Identify the exact model and current firmware version of the ZTE device (R5300g4, R5500g4, or R8500g4).
2. Visit the official ZTE support portal at support.zte.com.cn to check for available firmware updates.
3. Download the latest available firmware version for the specific device model.
4. Review the firmware release notes to confirm the version includes a fix for CVE-2020-6871 (authentication bypass).
5. Follow ZTE's standard firmware upgrade procedure, typically via the web management interface or CLI.
6. After upgrading, verify that the authentication vulnerability is resolved by testing the authentication mechanism.

Caveat Before upgrading, backup current configuration; firmware upgrades may reset device to factory defaults requiring reconfiguration

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

Fix this in R8500g4 Firmware Scoped from the published advisory

Consultation4.0 h
Implementation8.0 h
Testing6.0 h
Review / QA2.0 h

20.0 hours of engineering $3,500

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Scan for this in your stack

Free · runs locally

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References

Primary sources

support.zte.com.cnVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-6871 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2020-6871?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

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

At a glance

A fix existsA vendor remedy is published

Severity 9.8 Critical

Exploit likelihood EPSS, next 30 days 1.9%

Affects: R8500g4 Firmware

Remediation

A high-priority fix

Fix this in R8500g4 Firmware 20 hrs · Moderate

Typical engagement from $3,500

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2020-6871 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References