CVE-2019-17621
CVE-2019-17621 is a security flaw in D-Link DIR-859 Router, routers for homes and small offices. Attackers can run commands on D-Link DIR-859 Router from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 29 Jun 2023.[1]
D-Link DIR-859 Router is in things households have: home and small-office routers, so the fix matters at home as much as at work. D-Link has published a fix or advice.
Description
CISA calls it a command execution in D-Link DIR-859 Router. In its words: “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.”[1]
The underlying weakness is OS command injection (CWE-78), in MITRE’s list of common software weaknesses.[2]
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; D-Link’s advisory has them[3]. CISA names the product as D-Link DIR-859 Router.
Every device with D-Link DIR-859 Router needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 29 Jun 2023, 1,277 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 20 Jul 2023 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 91%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
D-Link has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions or discontinue use of the product if updates are unavailable.”[1]
- Update D-Link DIR-859 Router now.Open the router’s app, or its admin page in a browser, and look for a firmware update. Then turn on automatic updates, so the next fix arrives on its own.
- If the maker has stopped updating it, replace it.Routers stop getting fixes after a few years, and attackers keep a list of the ones that did. If there’s no newer firmware, it won’t be fixed.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 91%.[4] |
See also
Other D-Link DIR-859 Router flaws
- CVE-2024-0769: path traversal ·
Other D-Link flaws
- CVE-2025-29635, D-Link DIR-823X: command injection ·
- CVE-2022-37055, D-Link Routers: buffer overflow ·
- CVE-2022-40799, D-Link DNR-322L: download of code without integrity check ·
- CVE-2020-25079, D-Link DCS-2530L and DCS-2670L Devices: DCS-2530L and DCS-2670L command injection ·
- CVE-2020-25078, D-Link DCS-2530L and DCS-2670L Devices: unspecified ·
Other OS command injection flaws
- CVE-2026-110447, Collabora Online – Built-in CODE Server: online – built-in CODE server OS command injection ·
- CVE-2026-106931, EG Secure Solutions SiteGuard Server Edition: OS command injection ·
- CVE-2026-83549, SonicWall SMA1000 Appliances: OS command injection ·
- CVE-2026-49869, Kestra OSS: OSS OS command injection ·
- CVE-2026-73570, Synacor Zimbra Collaboration Suite (ZCS): OS command injection ·
Added the same day
- CVE-2021-25489, Samsung Mobile Devices: improper input validation ·
- CVE-2021-25487, Samsung Mobile Devices: out-of-bounds read ·
- CVE-2021-25395, Samsung Mobile Devices: race condition ·
- CVE-2021-25394, Samsung Mobile Devices: race condition ·
- CVE-2021-25372, Samsung Mobile Devices: improper boundary check ·
Every D-Link flaw on CISA’s list · Everything added in June 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “D-Link DIR-859 Router Command Execution Vulnerability”. Known Exploited Vulnerabilities Catalog, added 29 Jun 2023.
- ^ National Institute of Standards and Technology. “CVE-2019-17621 Detail”. National Vulnerability Database, published 30 Dec 2019.
- ^ D-Link. Advisories and fixes: supportannouncement.us.dlink.com, supportannouncement.us.dlink.com, dlink.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.906, percentile 99.8, 31 Oct 2026.
- CVE Program. “CVE-2019-17621”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.