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Vmg3312 T20a FirmwareOperating system · Zyxel

CVE-2022-26413

HIGH · 8.0 CVSS v3.1 Published 2022-04-11
Fix available
A fix is available. Upgrade to 5.13 / 5.17 or later.
See remediation →
82/100
Remediation priority · High
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 command injection vulnerability in the CGI program of Zyxel VMG3312-T20A firmware version 5.30(ABFX.5)C0 could allow a local authenticated attacker to execute arbitrary OS commands on a vulnerable device via a LAN interface.

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

A command injection vulnerability exists in the CGI program of Zyxel VMG3312-T20A routers running firmware version 5.30(ABFX.5)C0. The vulnerability allows a locally authenticated attacker on the LAN to inject and execute arbitrary operating system commands through unsanitized input being passed to system calls in the CGI program.

MitigationApply the vendor-supplied firmware patch when available. Until then, limit device access to trusted authenticated users only and monitor for unusual command activity on the LAN segment.

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
Vmg3312 T20a FirmwareOperating system
Affected:= 5.30\(abfx.5\)c0
Emg3525 T50b FirmwareOperating system
Affected:< 5.50\(abpm.6\)c0
Emg5523 T50b FirmwareOperating system
Affected:< 5.50\(abpm.6\)c0
Emg5723 T50k FirmwareOperating system
Affected:< 5.50\(abom.7\)c0
Emg6726 B10a FirmwareOperating system
Affected:< 5.13\(abnp.7\)c0
Vmg1312 T20b FirmwareOperating system
Affected:< 5.50\(absb.5\)c0
Vmg3625 T50b FirmwareOperating system
Affected:< 5.50\(abpm.6\)c0
Vmg3927 B50a FirmwareOperating system
Affected:< 5.17\(abmt.6\)c0

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
Adjacent
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:L/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 device model
    Access the router web interface or check the device label. Look for model number such as VMG3312-T20A, EMG3525-T50B, EMG5523-T50B, EMG5723-T50K, EMG6726-B10A, VMG1312-T20B, VMG3625-T50B, or VMG3927-B50A.
    Affected if The device model is NOT one of these eight affected models.
  2. Determine firmware version
    Log into the router web interface and navigate to Status or Maintenance > Firmware Upgrade page. Alternatively, check the firmware file name or use the router's command line if accessible.
    Affected if For VMG3312-T20A the version equals 5.30(ABFX.5)C0 exactly, OR for any other affected model the version is lower than the stated threshold (5.50(ABPM.6)C0, 5.50(ABOM.7)C0, 5.13(ABNP.7)C0, 5.50(ABSB.5)C0, or 5.17(ABMT.6)C0).
  3. Verify web CGI interface is accessible
    Attempt to access the router's web interface from a LAN-connected host using HTTP or HTTPS. The vulnerability exists in the CGI program, so the web interface must be reachable.
    Affected if The router web interface/CGI is accessible from the LAN and responds to requests.

Your device is affected if it is one of the eight listed models AND its firmware version falls within the specified vulnerable range, and the web interface is accessible from the LAN.

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 5.13 / 5.17 / 5.50 or later
Fixed in 5.135.175.50
Interim mitigation

Apply the vendor-supplied firmware patch when available. Until then, limit device access to trusted authenticated users only and monitor for unusual command activity on the LAN segment.

Recommended fix Moderate confidence

Zyxel firmware version 5.50 or later for T50b/T20b models, version 5.13 or later for EMG6726-B10a, version 5.17 or later for VMG3927-B50a, or the latest available stable release from Zyxel for your specific model

  1. 1. Identify the exact model number of your Zyxel device from the affected list (VMG3312-T20a, EMG3525-T50b, EMG5523-T50b, EMG5723-T50k, EMG6726-B10a, VMG1312-T20b, VMG3625-T50b, or VMG3927-B50a).
  2. 2. Access the device's web management interface or administrative console.
  3. 3. Navigate to the firmware upgrade or system maintenance section.
  4. 4. Download the latest firmware version from the official Zyxel support website (www.zyxel.com) for your specific model.
  5. 5. Upload and apply the firmware update, ensuring uninterrupted power during the process.
  6. 6. After the device reboots, verify the new firmware version is installed correctly.
  7. 7. Confirm the vulnerability is remediated by checking that the CGI program no longer allows command injection.
Caveat Upgrading firmware may reset some custom configurations; backup current settings before upgrading and reapply after the update

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

Fix this in Vmg3312 T20a Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,600
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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-2022-26413 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