dbcve.org
UosOperating system · Zyxel

CVE-2025-1731

HIGH · 7.8 CVSS v3.1 Published 2025-04-22
Fix available
A fix is available. Upgrade to 1.32 or later.
See remediation →
80/100
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
An incorrect permission assignment vulnerability in the PostgreSQL commands of the Zyxel USG FLEX H series uOS firmware versions from V1.20 through V1.31 could allow an authenticated local attacker with low privileges to gain access to the Linux shell and escalate their privileges by crafting malicious scripts or modifying system configurations with administrator-level access through a stolen token. Modifying the system configuration is only possible if the administrator has not logged out and the token remains valid.

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 · moderate confidence

This is a local privilege escalation vulnerability in Zyxel USG FLEX H series firewalls. An authenticated attacker with low privileges can exploit incorrect permission assignments in PostgreSQL commands to gain Linux shell access and escalate to administrator-level privileges by crafting malicious scripts or modifying system configurations using a stolen valid admin token.

MitigationApply firmware update to V1.32 or later to patch the permission assignment flaw in PostgreSQL commands; until then, enforce strict session timeouts and ensure administrators log out immediately after use to invalidate tokens.

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:>= 1.20, < 1.32

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/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 Zyxel Uos version
    Access the device admin interface or use the CLI command to retrieve the firmware/OS version. Compare the installed version against the affected range: versions 1.20 and above but below 1.32 are vulnerable.
    Affected if The installed Zyxel Uos version is 1.20 or higher but lower than 1.32
  2. Verify PostgreSQL database usage
    Check if the device has PostgreSQL database functionality enabled or configured. This may be visible in the device management interface under database settings, or via CLI commands that list running database services.
    Affected if PostgreSQL is actively used on the device for storing configuration or user data
  3. Review user account privileges
    Examine the user management section to identify accounts with low-privilege roles. Check whether non-administrator accounts have access to system configuration or script execution features.
    Affected if Low-privilege user accounts exist on the device with access to configuration or scripting features
  4. Inspect for unauthorized scripts or configurations
    Review any user-created scripts, scheduled tasks, or modified system configuration files that may have been injected. Look for scripts with elevated execution permissions or unexpected system modifications.
    Affected if Unauthorized scripts, unexpected configurations, or modified system files are present that were not created by legitimate administrators

You are affected if your Zyxel Uos version is 1.20 or higher but below 1.32, and the device uses PostgreSQL with low-privilege accounts that can access configuration or scripting features.

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 1.32 or later
Fixed in 1.32
Interim mitigation

Apply firmware update to V1.32 or later to patch the permission assignment flaw in PostgreSQL commands; until then, enforce strict session timeouts and ensure administrators log out immediately after use to invalidate tokens.

Recommended fix High confidence

Uos V1.32 or later

  1. Obtain the fixed firmware version (V1.32 or later) from Zyxel's official support website for the USG FLEX H series
  2. Review Zyxel's firmware upgrade documentation for USG FLEX H series devices
  3. Backup the current device configuration before proceeding with the upgrade
  4. Upload and install the V1.32 or later firmware through the device's administrative interface
  5. Verify the firmware upgrade was successful by checking the installed version
  6. Ensure administrator sessions are properly managed after upgrade to maintain security

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

Fix this in Uos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,330
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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-2025-1731 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