# CVE-2019-17621 **CISA KEV** > As of 2025-10-21, CVE-2019-17621 is a CRITICAL-severity vulnerability, CVSS v3.1 9.8, EPSS 89.6% (99.7th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-06-29), with a US federal remediation deadline of 2023-07-20. Threadlinqs Intelligence links 2 tracked threat campaigns to CVE-2019-17621, most recently “ClingSTUN Linux Backdoor Turns Unpatched IoT Devices Into Proxy Nodes via Public STUN Infrastructure”. **Last updated:** 2025-10-21 ## What is 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. The record classifies CVE-2019-17621 under weakness class [CWE-78](https://intel.threadlinqs.com/cwe/CWE-78). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. The identifier was first published 2490 days ago. ## Severity and exploitation probability - **CVSS v3.1 base score:** 9.8 — CRITICAL (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`) - **EPSS (FIRST):** 89.6% probability of exploitation in the next 30 days, higher than 99.7% of all scored CVEs - **CISA KEV:** Listed since 2023-06-29, federal remediation deadline 2023-07-20 - **Threadlinqs priority:** 9/10 — CISA KEV-listed, which Threadlinqs floors at 9 - **Published:** 2019-12-30, last modified 2025-10-21 ## Is CVE-2019-17621 being exploited? CISA added CVE-2019-17621 to the Known Exploited Vulnerabilities catalog on 2023-06-29, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2023-07-20 under BOD 22-01. Weaponised exploit code for CVE-2019-17621 is publicly available. 2 public proof-of-concept repositories are tracked for this identifier. It currently carries a trending score of 53 in the Threadlinqs vulnerability feed. - [Squirre17/CVE-2019-17621](https://github.com/Squirre17/CVE-2019-17621) (github) - [trickest/cve](https://github.com/trickest/cve/blob/main/2019/CVE-2019-17621.md) (trickest) ## Affected products and versions No affected-product or package list has been recorded for CVE-2019-17621 in the tracked sources. The vendor advisory and the references below are the authoritative statement of what is affected. ## How to fix CVE-2019-17621 Because CVE-2019-17621 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2023-07-20. No vendor patch reference has been recorded for CVE-2019-17621 in the tracked sources. Follow the references below for a fix, and treat any affected deployment as exposed until the vendor states otherwise. ## Threat activity tracking CVE-2019-17621 2 tracked threats in the Threadlinqs corpus reference CVE-2019-17621, either in the campaign’s CVE list or as an indicator on the campaign record. - [ClingSTUN Linux Backdoor Turns Unpatched IoT Devices Into Proxy Nodes via Public STUN Infrastructure](https://intel.threadlinqs.com/threat/TL-2026-2934) — HIGH · 2026-10-05 - [Cling IoT botnet masquerades as Google STUN traffic for C2, exploiting Realtek Jungle SDK CVE-2021-35394](https://intel.threadlinqs.com/threat/TL-2026-2857) — CRITICAL · 2026-10-03 ## Sources Enriched from CVE.org, FIRST EPSS, CISA KEV, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-10-10. **Vendor advisory and patch** - [supportannouncement.us.dlink.com](https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10147) - [supportannouncement.us.dlink.com (publication)](https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10146) **Other references** - [ftc.gov](https://www.ftc.gov/system/files/documents/cases/dlink_proposed_order_and_judgment_7-2-19.pdf) - [dlink.com](https://www.dlink.com/en/security-bulletin) - [medium.com](https://medium.com/%40s1kr10s/d-link-dir-859-rce-unautenticated-cve-2019-17621-en-d94b47a15104) - [medium.com (d link dir 859 rce unautenticated cve 20)](https://medium.com/%40s1kr10s/d-link-dir-859-rce-unautenticated-cve-2019-17621-es-fad716629ff9) - [packetstormsecurity.com](http://packetstormsecurity.com/files/156054/D-Link-DIR-859-Unauthenticated-Remote-Command-Execution.html) Canonical: https://intel.threadlinqs.com/cve/CVE-2019-17621 Full detection coverage and IOCs for threats exploiting CVE-2019-17621 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp