dbcve.org
T10 FirmwareOperating system · Totolink

CVE-2025-9533

CRITICAL · 9.8 CVSS v3.1 Published 2025-08-27
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 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 vulnerability has been found in TOTOLINK T10 4.1.8cu.5241_B20210927. Affected is an unknown function of the file /formLoginAuth.htm. The manipulation of the argument authCode with the input 1 leads to improper authentication. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used.

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 TOTOLINK T10 router firmware 4.1.8cu.5241_B20210927 contains an authentication bypass vulnerability in the /formLoginAuth.htm web interface. The authCode parameter accepts a value of '1' to bypass authentication checks, allowing remote attackers to gain administrative access to the device without valid credentials.

MitigationUsers should immediately update the firmware to a patched version once available, or disable remote web management and restrict access to trusted networks. Until a patch is released, network segmentation and firewall rules should be used to limit exposure to the router's web interface.

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
T10 FirmwareOperating system
Affected:= 4.1.8cu.5241_b20210927

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 router model
    Access the router's web interface or check the device label/marketing materials to confirm the model is TOTOLINK T10
    Affected if The device is not a TOTOLINK T10 router (this CVE does not apply)
  2. Check the installed firmware version
    Log into the router's web interface and navigate to the firmware/version status page, or use the router's admin CLI if available, and note the exact firmware version string
    Affected if The firmware version is 4.1.8cu.5241_b20210927 (exact match)
  3. Verify the web management interface is reachable
    Attempt to access the router's IP address on port 80 or 443 from a connected client, or test remote access if remote management is enabled
    Affected if The web interface is unreachable (the vulnerability cannot be exploited if the interface is not accessible)
  4. Confirm remote web management exposure
    Check the router's administrative settings for 'remote management', 'web access from WAN', or similar options; test by attempting to reach the web interface from an external network/IP
    Affected if Remote web management is enabled and the interface is accessible from the internet (this increases exposure to remote attackers)
  5. Test the vulnerable endpoint (optional confirmation)
    Send a POST request to /formLoginAuth.htm with the parameter authCode=1, or attempt to access protected pages after supplying this parameter value
    Affected if The authentication is successfully bypassed and admin access is granted without valid credentials

You are affected if you are running TOTOLINK T10 firmware version 4.1.8cu.5241_b20210927 and the router's web interface is accessible (especially remotely), since the authCode parameter in /formLoginAuth.htm can bypass authentication.

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

Users should immediately update the firmware to a patched version once available, or disable remote web management and restrict access to trusted networks. Until a patch is released, network segmentation and firewall rules should be used to limit exposure to the router's web interface.

Fix this in T10 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,120
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,392.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-9533 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2025-9533 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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