dbcve.org
Di 8100 FirmwareOperating system · Dlink

CVE-2025-7911

CRITICAL · 9.8 CVSS v3.1 Published 2025-07-20
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 classified as critical was found in D-Link DI-8100 1.0. This vulnerability affects the function sprintf of the file /upnp_ctrl.asp of the component jhttpd. The manipulation of the argument remove_ext_proto/remove_ext_port leads to stack-based buffer overflow. 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 · moderate confidence

A stack-based buffer overflow vulnerability exists in the D-Link DI-8100 router (version 1.0) within the jhttpd web server component. The unsafe sprintf function in /upnp_ctrl.asp does not properly validate the length of the remove_ext_proto and remove_ext_port arguments, allowing an attacker to overflow the stack buffer. This critical flaw is remotely exploitable without authentication and may allow remote code execution.

MitigationApply the vendor firmware patch when available; if no patch exists, consider network segmentation, disabling UPnP, or replacing the device, as this critical flaw is actively being exploited.

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
Di 8100 FirmwareOperating system
Affected:= 1.0

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 device model and firmware version
    Access the router web interface (typically http://192.168.0.1) and navigate to System > Status or Device Info to find the firmware version. Alternatively, check via CLI if accessible, or look for version sticker on device.
    Affected if Firmware version is exactly 1.0 (the only affected version listed)
  2. Confirm jhttpd web server is running
    Use a network scanner or check router status page to verify the web server service is active. You can also attempt to access the router's web interface from a connected host.
    Affected if The web server is accessible and responding on HTTP/HTTPS ports (default 80/443)
  3. Verify UPnP is enabled
    Log into the router web interface and navigate to Advanced > UPnP or similar section to check if Universal Plug and Play is turned on. The vulnerable code path in /upnp_ctrl.asp handles UPnP port forwarding configuration.
    Affected if UPnP feature is enabled on the device
  4. Check for presence of vulnerable endpoint
    Attempt to access http://<router-ip>/upnp_ctrl.asp from a connected client. This endpoint handles remove_ext_proto and remove_ext_port parameters.
    Affected if The /upnp_ctrl.asp page returns successfully (status 200) and accepts parameters

The device is affected if it is a D-Link DI-8100 router running firmware version 1.0 with the web server and UPnP both enabled, allowing access to the vulnerable /upnp_ctrl.asp endpoint.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor firmware patch when available; if no patch exists, consider network segmentation, disabling UPnP, or replacing the device, as this critical flaw is actively being exploited.

Recommended fix Moderate confidence
  1. 1. Check D-Link's official support page for the DI-8100 for any available firmware updates
  2. 2. If no official firmware update is available, consider replacing the device as DI-8100 may be End-of-Life (EOL)
  3. 3. If the device must remain in service, implement network-level filtering to block external access to UPnP services (port 1900 and any custom ports)
  4. 4. Disable UPnP functionality in the device configuration if possible
  5. 5. Place the device behind a properly configured firewall with restrictive inbound rules
  6. 6. Monitor for any security advisories from D-Link regarding this vulnerability
Caveat The DI-8100 is an older device (released circa 2012-2014) and may be End-of-Life with no firmware update available. Replacement with a currently supported device is recommended.

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

Fix this in Di 8100 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
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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-2025-7911 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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