Vulnerability report

Exploited in the wild High confidence Not in CISA KEV

CVE-2026-0625

DSL-2640B Authentication Bypass

D-Link / DSL-2640B · 0

Watch CVE-2026-0625 Browse KEV feed
Severity
CVSS 9.3 · Critical
Confidence
High
Exploit status
Exploited in the wild
EPSS
1.0%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-0625 is an unauthenticated vulnerability affecting D-Link DSL-2640B and 16 other products. Multiple D-Link DSL/DIR/DNS devices contain an authentication bypass and improper access control vulnerability in the...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is high. Also confirmed by third-party sources.

Who is affected?

D-Link / DSL-2640B 0.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

DSL-2640B Authentication Bypass

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).

D-Link Affected
DSL-2640B
0
D-Link Affected
DSL-2740R
0
D-Link Affected
DSL-2780B
0
D-Link Affected
DSL-526B
0
D-Link Affected
DSL-2640T
0
D-Link Affected
DSL-500
0
D-Link Affected
DSL-500G
0
D-Link Affected
DSL-502G
0
D-Link Affected
DIR-905L
0
D-Link Affected
DIR-600
0
D-Link Affected
DIR-608
0
D-Link Affected
DIR-610
0
D-Link Affected
DIR-611
0
D-Link Affected
DIR-615
0
D-Link Affected
DNS-320
0
D-Link Affected
DNS-325
0
D-Link Affected
DNS-345
0
View vendor advisory (opens in new tab)
Published
05 Jan 2026
Exploitation Reported
01 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CVE

Recorded 01 Jun 2026

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
CVE First 2026-06-01 10:47 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

9.3 Critical

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

1.0%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Missing Authentication for Critical Function CWE-306

Timeline

From disclosure to observed exploitation

  1. 10:47 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  2. 21:14 UTC

    CVE published

    Vulnerability disclosed publicly

  3. 20:59 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-0625

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-0625",
  "confidence": "High",
  "cvss_score": 9.3,
  "cvss_estimated": false,
  "epss_score": 0.00972,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}