Known exploited · D-Link

CVE-2019-17621: D-Link DIR-859 Router Command Execution Vulnerability

What it is

D-Link DIR-859 router contains a command execution vulnerability in the UPnP endpoint URL, /gena.cgi. Exploitation 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.

Added June 29, 2023Due July 20, 2023CISA KEV catalog 2026.10.01

Vendor: D-Link
Product: DIR-859 Router
Added to KEV: June 29, 2023
CISA due date: July 20, 2023
Ransomware use: Unknown
Weakness: CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

What CISA requires

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

Forensic triage

What to do now

Find every instance of DIR-859 Router you run, including the forgotten ones, and check its version against the vendor advisory.
Apply the vendor's fix or mitigation, before July 20, 2023 if you are bound by CISA's deadline, sooner if it faces the internet.
Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
Until every instance is patched, block the attack at the edge: a WAF in blocking mode stops OS command injection payloads, including Shellshock.

References

CVE-2019-17621 in the National Vulnerability Database

The Dome

Block it at the edge while you patch

The Dome's WAF runs the OWASP Core Rule Set in blocking mode and stops OS command injection payloads, including Shellshock before they reach your application.

See the Dome

T Academy

Train the engineers who fix it

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Source: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.