CVE-2022-40740
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 · uneditedRealtek GPON router has insufficient filtering for special characters. A remote attacker authenticated as an administrator can exploit this vulnerability to perform command injection attacks, to execute arbitrary system command, manipulate system or disrupt service.
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 confidenceRealtek GPON routers contain a command injection vulnerability where insufficient filtering of special characters in input fields allows an authenticated administrator to escape intended command boundaries and execute arbitrary system commands on the underlying Linux-based firmware.
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= 1.0= 2.0= 2.2= 1.9= 3.3= 4.0= 4.1CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify the device as a Realtek GPON routerAccess the device administrative web interface or physically inspect the device labeling to confirm the manufacturer is Realtek and the device type is a GPON optical network terminal/routerAffected if The device is a Realtek GPON router or optical network terminal (ONT)
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Locate the firmware or SDK versionLog into the administrative web interface and navigate to System Settings, Device Info, or Status pages to find the firmware version, SDK version, or software build informationAffected if The displayed firmware or SDK version matches one of the affected versions: Realtek Usdk 1.0, 2.0, or 2.2; or Realtek Xpon SDK 1.9, 3.3, 4.0, or 4.1
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Verify administrative web interface is accessibleConfirm the device web management interface is reachable on the expected IP address (typically the LAN or WAN interface IP) via HTTP or HTTPSAffected if The administrative web interface is network-accessible (even from a restricted management VLAN)
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Confirm authentication capability existsDetermine whether valid administrator credentials can be supplied to the login page of the web interfaceAffected if An authenticated administrator session can be established, as the vulnerability requires authenticated access to input fields
The environment is affected if the device is a Realtek GPON router running any of the listed Usdk (1.0, 2.0, 2.2) or Xpon SDK (1.9, 3.3, 4.0, 4.1) versions and the administrative web interface is accessible with valid credentials.
Generated from the published advisory. Verify against your own configuration.
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 dataApply the vendor-supplied firmware patch for Realtek GPON routers; if no patch is available, restrict administrative web interface access to trusted IP addresses or networks to reduce attack surface.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2022-40740 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2022-40740 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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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