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AsuswrtOperating system · Asus

CVE-2018-20334

CRITICAL · 9.8 CVSS v3.1 Published 2020-03-20
No fix yet
No fix has been published. The vendor has not shipped a fixed release or patch. You remain exposed.
See remediation →
100/100
Remediation priority · Urgent
Public exploit 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 issue was discovered in ASUSWRT 3.0.0.4.384.20308. When processing the /start_apply.htm POST data, there is a command injection issue via shell metacharacters in the fb_email parameter. By using this issue, an attacker can control the router and get shell.

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
How this class of weakness works · CWE-78

User input reaches a shell or system command without being fully separated from the command itself, so an attacker can append their own instructions. Because these run with the application's privileges, it often means full control of the host. The lasting fix is to avoid the shell entirely — call APIs directly and pass arguments as data, never as concatenated strings.

General guidance for the os command injection class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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
AsuswrtOperating system
Affected:= 3.0.0.4.384.20308

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

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
Recommended fix Moderate confidence

Latest ASUSWRT firmware available from asus.com for your specific router model ( ASUS releases security patches in routine firmware updates; CVE-2018-20308 was addressed in subsequent releases after 3.0.0.4.384.20308)

  1. 1. Identify your exact ASUS router model number (located on the device label or in the web GUI)
  2. 2. Visit the official ASUS support page at https://www.asus.com/supportonly/ (or search for your model on asus.com)
  3. 3. Download the latest available ASUSWRT firmware for your router model
  4. 4. Access the router's web administration interface (typically at 192.168.1.1)
  5. 5. Navigate to Administration > Firmware Upgrade
  6. 6. Upload and apply the new firmware version
  7. 7. After reboot, verify the firmware version in the Administration section matches the downloaded version
Caveat firmware upgrades on ASUS routers typically preserve settings, but always backup configuration before upgrading; some older models may have limited firmware support lifecycle

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

No vendor fix exists Asuswrt has not published a patch for this.

There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.

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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-2018-20334 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
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