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Missing AuthenticationWeakness · CWE-306

CVE-2026-0625

CRITICAL · 9.3 CVSS v4.0 Published 2026-01-05
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
Multiple D-Link DSL/DIR/DNS devices contain an authentication bypass and improper access control vulnerability in the dnscfg.cgi endpoint that allows an unauthenticated attacker to access DNS configuration functionality. By directly requesting this endpoint, an attacker can modify the device’s DNS settings without valid credentials, enabling DNS hijacking (“DNSChanger”) attacks that redirect user traffic to attacker-controlled infrastructure. In 2019, D-Link reported that this behavior was leveraged by the "GhostDNS" malware ecosystem targeting consumer and carrier routers. All impacted products were subsequently designated end-of-life/end-of-service, and no longer receive security updates. Exploitation evidence was observed by the Shadowserver Foundation on 2025-11-27 (UTC).

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 confidence

D-Link DSL/DIR/DNS devices contain an authentication bypass vulnerability in the dnscfg.cgi endpoint that allows unauthenticated attackers to modify DNS settings, enabling DNS hijacking attacks that redirect traffic to malicious infrastructure. This was exploited by the GhostDNS malware ecosystem in 2019 and was observed in the wild by Shadowserver Foundation in November 2025.

MitigationDevices are end-of-life with no security updates available; affected devices should be replaced with supported hardware. Network-level DNS filtering and monitoring can provide interim protection.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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 your D-Link device model
    Check the device label or web interface for the model number (DSL, DIR, or DNS series)
    Affected if Device is a D-Link DSL, DIR, or DNS series router
  2. Confirm dnscfg.cgi endpoint is exposed
    Attempt to access http://<device-ip>/dnscfg.cgi from an internal network host
    Affected if Endpoint responds with any HTTP status (200, 401, or error page) rather than a connection failure
  3. Test DNS configuration modification without authentication
    Send a POST request to dnscfg.cgi with DNS parameters (such as dns_primary= and dns_secondary=) without providing any authentication cookies or credentials
    Affected if Request succeeds and returns success response or modifies DNS settings without requiring login
  4. Inspect current DNS server settings
    Access the device web interface or check DNS configuration via command: grep dns /etc/config/network or similar on the device
    Affected if Primary DNS server is set to an IP address you did not configure or is different from your ISP-assigned values
  5. Verify remote management is enabled
    Check device settings for 'Remote Management' or 'Web Access' enabled on WAN interface (typically under Administration > System or Management settings)
    Affected if Remote management is enabled and accessible from WAN on ports 80/443

You are affected if you use a D-Link DSL, DIR, or DNS series device where dnscfg.cgi allows unauthenticated DNS configuration changes.

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

Devices are end-of-life with no security updates available; affected devices should be replaced with supported hardware. Network-level DNS filtering and monitoring can provide interim protection.

Recommended fix High confidence
  1. Isolate affected D-Link devices on a restricted VLAN or behind a firewall to limit external network exposure
  2. Disable remote web management if not required - access the router's administration interface and turn off "Remote Management" or "Web Access" from WAN
  3. Implement network segmentation to place the affected device in a DMZ or isolated network segment
  4. Monitor network traffic for suspicious DNS configuration changes using intrusion detection systems
  5. Consider replacing EOL D-Link devices with currently supported hardware from vendors that provide regular security updates
  6. If the device must remain in service, configure upstream network equipment to block external access to the device's WAN IP on ports 80/443
Caveat All affected D-Link products (DSL/DIR/DNS series) are end-of-life and receive no security updates from the vendor; replacement with supported hardware is the only durable remediation

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

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing4.0 h
  • Review / QA2.0 h
26.0 hours of engineering $4,640
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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-2026-0625 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
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  • No spam, self-promotion, credentials, or personal data