CVE-2017-6884
CVE-2017-6884 is a security flaw in Zyxel EMG2926 Routers, firewalls and routers for homes and small businesses. Attackers can run commands on Zyxel EMG2926 Routers. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 18 Sep 2023, and says ransomware gangs have used it.[1]
Zyxel EMG2926 Routers is in things households have: home and small-office routers, so the fix matters at home as much as at work. Zyxel has published a fix or advice.
Description
CISA calls it a command injection in Zyxel EMG2926 Routers. In its words: “Zyxel EMG2926 routers contain a command injection vulnerability located in the diagnostic tools, specifically the nslookup function. A malicious user may exploit numerous vectors to execute malicious commands on the router, such as the ping_ip parameter to the expert/maintenance/diagnostic/nslookup URI.”[1]
The CVE record adds: “A command injection vulnerability was discovered on the Zyxel EMG2926 home router with firmware V1.00(AAQT.4)b8. The vulnerability is located in the diagnostic tools, specifically the nslookup function. A malicious user may exploit numerous vectors to execute arbitrary commands on the router, such as the ping_ip parameter to the expert/maintenance/diagnostic/nslookup URI.”[2]
The underlying weakness is OS command injection (CWE-78), in MITRE’s list of common software weaknesses.
It scores 8.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Zyxel’s advisory has them[3]. CISA names the product as Zyxel EMG2926 Routers.
Every device with Zyxel EMG2926 Routers needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 18 Sep 2023, 2,356 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 9 Oct 2023 to fix it.[1] CISA says ransomware gangs have used it.
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 33%. That’s in the top 2% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Zyxel has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Update Zyxel EMG2926 Routers 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 8.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[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 33%.[4] |
See also
Other Zyxel flaws
- CVE-2026-7273, Zyxel GS1900 Series Switches: stack-based buffer overflow ·
- CVE-2024-40891, Zyxel DSL CPE Devices: DSL CPE OS command injection ·
- CVE-2024-40890, Zyxel DSL CPE Devices: DSL CPE OS command injection ·
- CVE-2024-11667, Zyxel Multiple Firewalls: path traversal ·
- CVE-2017-18368, Zyxel P660HN-T1A Routers: command injection ·
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-2022-22265, Samsung Mobile Devices: use-after-free ·
- CVE-2021-3129, Laravel Ignition: file upload ·
- CVE-2014-8361, Realtek SDK: improper input validation ·
Every Zyxel flaw on CISA’s list · Everything added in September 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “Zyxel EMG2926 Routers Command Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 18 Sep 2023.
- ^ National Institute of Standards and Technology. “CVE-2017-6884 Detail”. National Vulnerability Database, published 6 Apr 2017.
- ^ Zyxel. Advisories and fixes: zyxel.com, zyxelguard.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.330, percentile 98.4, 31 Oct 2026.
- CVE Program. “CVE-2017-6884”. 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.