Rt Ac88u FirmwareOperating system · Asus

CVE-2020-29656

HIGH · 7.5 CVSS v3.1 Published 2020-12-09
Fix available
A fix is available. Upgrade to 3.1.0.108 or later.
See remediation →
84/100
Remediation priority · High
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
An information disclosure vulnerability exists in RT-AC88U Download Master before 3.1.0.108. A direct access to /downloadmaster/dm_apply.cgi?action_mode=initial&download_type=General&special_cgi=get_language makes it possible to reach "unknown functionality" in a "known to be easy" manner via an unspecified "public exploit."

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

An information disclosure vulnerability in ASUS RT-AC88U Download Master versions before 3.1.0.108 allows unauthenticated attackers to access an unknown functionality via direct requests to /downloadmaster/dm_apply.cgi with specific parameters (action_mode=initial, download_type=General, special_cgi=get_language). The vulnerability is described as easily exploitable.

MitigationUpdate ASUS RT-AC88U Download Master to version 3.1.0.108 or later to patch the information disclosure vulnerability. If patching is not immediately possible, restrict network access to the Download Master CGI interfaces.

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
Rt Ac88u FirmwareOperating system
Affected:< 3.1.0.108

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
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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
    Check the router model through the web interface (typically at http://192.168.1.1) or via the admin panel. Look for 'RT-AC88U' in the device model or system information section.
    Affected if The device is not an ASUS RT-AC88U router, then this specific CVE does not apply.
  2. Confirm Download Master is installed
    Log into the router admin interface and navigate to the Download Master section (usually under USB application or Storage settings). Verify if Download Master is listed as installed or enabled.
    Affected if Download Master is not installed or not enabled on the router, then this vulnerability does not apply.
  3. Check the Download Master version
    In the Download Master settings page, locate the version information. This is typically displayed in the Download Master interface or in the system information section of the firmware.
    Affected if The Download Master version is before 3.1.0.108 (for example, 3.1.0.099 or earlier), the router is vulnerable to this information disclosure issue.
  4. Verify network accessibility of the CGI endpoint
    Attempt to access http://[router-ip]/downloadmaster/dm_apply.cgi from an external network location, or check router firewall settings to determine if port 80/443 is exposed to the internet.
    Affected if The Download Master CGI interface is exposed to untrusted networks (such as the internet), an unauthenticated attacker could exploit this vulnerability.

A user is affected if they have an ASUS RT-AC88U router with Download Master installed and the version is before 3.1.0.108, especially if the router admin interface is network-accessible.

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
Upgrade available Upgrade to 3.1.0.108 or later
Fixed in 3.1.0.108
Interim mitigation

Update ASUS RT-AC88U Download Master to version 3.1.0.108 or later to patch the information disclosure vulnerability. If patching is not immediately possible, restrict network access to the Download Master CGI interfaces.

Fix this in Rt Ac88u Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,770
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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-2020-29656 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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