Threats / D-Link / CVE-2021-40655
CVE-2021-40655
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
D-Link DIR-605 Router vulnerability
D-Link DIR-605 routers contain an information disclosure vulnerability allowing attackers to obtain credentials by forging POST requests to /getcfg.php.
Verdict
Today item — known-exploited.
An unauthenticated attacker can retrieve administrative credentials from affected D-Link DIR-605 routers through a crafted request, enabling unauthorized access and device compromise. The vulnerability is actively exploited in the wild.
CISA KEV Yes · 2024-05-164EPSS 0.86659 (verify live)5CVSS 7.5 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: partial3Exploit Public PoC / detection · nuclei template12
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
5 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2024-05-16).
Probability (EPSS)
EPSS 0.86659 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) · Affected: D-Link, DIR-605 Router. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-863 Incorrect Authorization — weakness family: Authorization / access control.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: partialCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 965 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a POST request to the /getcfg.php endpoint on the target router to extract configuration data containing stored credentials.
Business
Administrative credentials are exposed, allowing complete compromise of network infrastructure and potential lateral movement into connected systems.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I use the obtained username and password to authenticate to the router's administrative interface and modify network settings.
Business
Attackers gain persistent control over network traffic, DNS resolution, and device configurations, enabling data interception and malware distribution.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05