What is CVE-2019-17621?

CVE-2019-17621 is a critical-severity vulnerability in Dlink Dir-818lx, classified under OS Command Injection. CVSS score: 9.8/10. Published 2019-12-30.

How severe is CVE-2019-17621?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2019-17621 known to be exploited?

Yes. CVE-2019-17621 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-06-29), indicating it is being actively exploited. 38 public proof-of-concept repositories are indexed.

RCE in Dlink Dir-818lx

CVE-2019-17621

The UPnP endpoint URL /gena.cgi in the D-Link DIR-859 Wi-Fi router 1.05 and 1.06B01 Beta01 allows an Unauthenticated remote attacker to execute system commands as root, by sending a specially crafted HTTP SUBSCRIBE request to the UPnP service when connecting to the local network.

Vulnerability class: Command Injection (OS Command Injection)

Published 2019-12-30 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.896 (99.8th percentile), scored 2026-10-19.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.896 · newest: 0.896 · change: 0.000

Affected products

Dlink Dir-818lx
Dlink Dir-818lx Firmware
Dlink Dir-822
Dlink Dir-822 Firmware
Dlink Dir-823
Dlink Dir-823 Firmware — versions 1.00b06
Dlink Dir-859
Dlink Dir-859 Firmware — versions 1.06b01
Dlink Dir-865l
Dlink Dir-865l Firmware

Weakness classification (CWE)

CWE-78 — OS Command Injection

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2023-06-29. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2023-07-20.

Required action: Apply updates per vendor instructions or discontinue use of the product if updates are unavailable.

Public proof-of-concept exploits

References

www.ftc.gov/system/files/documents/cases/dlink_proposed_order_and_judgment_7-2-… (US Government Resource, Third Party Advisory)
www.dlink.com/en/security-bulletin (Vendor Advisory)
supportannouncement.us.dlink.com/announcement/publication.aspx (Patch, Vendor Advisory)
supportannouncement.us.dlink.com/announcement/publication.aspx (Patch, Vendor Advisory)
medium.com/@s1kr10s/d-link-dir-859-rce-unautenticated-cve-2019-17621-en-d94b47a… (Exploit, Third Party Advisory)
medium.com/@s1kr10s/d-link-dir-859-rce-unautenticated-cve-2019-17621-es-fad7166… (Broken Link)
packetstormsecurity.com/files/156054/D-Link-DIR-859-Unauthenticated-Remote-Comm… (Exploit, VDB Entry, Third Party Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2019-17621?: CVE-2019-17621 is a critical-severity vulnerability in Dlink Dir-818lx, classified under OS Command Injection. CVSS score: 9.8/10. Published 2019-12-30.
How severe is CVE-2019-17621?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2019-17621 known to be exploited?: Yes. CVE-2019-17621 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-06-29), indicating it is being actively exploited. 38 public proof-of-concept repositories are indexed.