CVE-2023-51616
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 · uneditedD-Link DIR-X3260 prog.cgi SetSysEmailSettings Stack-Based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of D-Link DIR-X3260 routers. Authentication is required to exploit this vulnerability. The specific flaw exists within the prog.cgi binary, which handles HNAP requests made to the lighttpd webserver listening on TCP ports 80 and 443. The issue results from the lack of proper validation of a user-supplied string before copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-21593.
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 confidenceStack-based buffer overflow in the SetSysEmailSettings function of prog.cgi on D-Link DIR-X3260 routers. The vulnerability results from insufficient validation of user-supplied input before copying to a fixed-length stack buffer during HNAP request processing on the lighttpd webserver (ports 80/443). Successful exploitation requires authentication but yields code execution as root.
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< 1.04b01CVSS 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
- Adjacent
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/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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Check router firmware versionLog into the D-Link DIR-X3260 web admin interface (typically at http://192.168.0.1 or http://192.168.1.1). Navigate to the System or Firmware settings page and locate the firmware version displayed. Compare this version against the vulnerable threshold: any version below 1.04b01 is affected.Affected if Firmware version shown is below 1.04b01 (e.g., 1.04, 1.03, 1.02, etc.)
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Verify HNAP interface is accessibleSend an HTTP request to the router's web interface targeting the HNAP endpoint. This is typically at /HNAP1/ or can be identified by examining the router's web pages for HNAP form actions. Use an authenticated request to test if the interface responds.Affected if The HNAP endpoint returns a valid response (SOAP/XML) indicating the interface is enabled and reachable
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Confirm lighttpd webserver is running on ports 80/443Perform a network scan or use netstat/telnet to check if the router has open ports 80 (HTTP) and/or 443 (HTTPS). These ports host the lighttpd webserver that serves prog.cgi.Affected if Ports 80 or 443 are open and responding with the router's web login page or HNAP interface
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Identify if SetSysEmailSettings function is reachableExamine the prog.cgi binary or its behavior by sending a crafted HNAP request with the SetSysEmailSettings action. This requires valid admin credentials. The request typically contains email settings parameters that trigger the vulnerable function.Affected if You can authenticate to the router and successfully call the SetSysEmailSettings HNAP action, indicating the vulnerable code path is accessible
Your router is affected if it is a D-Link DIR-X3260 running firmware version below 1.04b01, has the HNAP web interface accessible on ports 80/443, and you can authenticate to trigger the SetSysEmailSettings function in prog.cgi.
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.
dbcve · scoped1.04b01
Apply vendor firmware update if available; otherwise implement compensating controls such as network segmentation to limit exposure, enforce strong authentication for HNAP interfaces, and monitor for exploitation attempts.
Firmware version 1.04b01 or later
- 1. Navigate to the D-Link DIR-X3260 router web interface (typically http://192.168.0.1 or http://192.168.1.1)
- 2. Log in with administrator credentials
- 3. Go to Maintenance > Firmware Upgrade or Settings > System > Firmware Update
- 4. Download the firmware version 1.04b01 or later from the official D-Link support website (support.dlink.com)
- 5. In the web interface, click 'Browse' to select the downloaded firmware file
- 6. Click 'Upload' or 'Upgrade' to begin the firmware update process
- 7. Wait for the upgrade to complete - do not power off the router during this process
- 8. The router will automatically reboot once the upgrade is finished
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2023-51616 — 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-2023-51616 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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- 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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