UosOperating system · Zyxel

CVE-2025-1732

MEDIUM · 6.7 CVSS v3.1 Published 2025-04-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
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
An improper privilege management vulnerability in the recovery function of the Zyxel USG FLEX H series uOS firmware version V1.31 and earlier could allow an authenticated local attacker with administrator privileges to upload a crafted configuration file and escalate privileges on a vulnerable device.

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

This is a local privilege escalation vulnerability in the recovery function of Zyxel USG FLEX H series firewall devices. An authenticated administrator can upload a crafted configuration file through the recovery function to gain higher privileges (likely root) on the device. The vulnerability stems from improper privilege validation in the recovery mechanism.

MitigationUpdate the Zyxel USG FLEX H series firmware to version V1.31_patch1 or later. Restrict administrative access to trusted personnel and monitor for unauthorized configuration uploads.

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
UosOperating system
Affected:= 1.31

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

CVSS:3.1/AV:L/AC:L/PR:H/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 device web interface or CLI and run 'get system-info' or check the device label/model to confirm it is a Zyxel USG FLEX H series firewall
    Affected if Device is not a USG FLEX H series model
  2. Check firmware version
    In the web interface go to Maintenance > Firmware or run 'show version' in CLI. Look for the firmware version number
    Affected if Firmware version is exactly 1.31 (Zyxel Uos)
  3. Verify recovery function status
    Navigate to Maintenance > Backup/Restore or Recovery in the web interface. Check if the recovery or configuration restore function is enabled and accessible
    Affected if Recovery function is exposed and accessible to administrators
  4. Review administrative accounts
    Check User/Administrator accounts in the device under Administration > Admin Users or run 'show admin' in CLI. Note the number and privileges of accounts
    Affected if Multiple administrator accounts exist with varying privilege levels that could be exploited

The device is affected if it is a USG FLEX H series running Zyxel Uos version 1.31 and the recovery/configuration restore function is accessible to authenticated administrators.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update the Zyxel USG FLEX H series firmware to version V1.31_patch1 or later. Restrict administrative access to trusted personnel and monitor for unauthorized configuration uploads.

Fix this in Uos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
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Scan for this in your stack

Free · runs locally
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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-2025-1732 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
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  • Version or environment caveats, and links to real fixes
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