Recent ZyXEL Switch Vulnerability Exploited by Chinese Hackers
Source SecurityWeek
Exploited in the wild · KEV due 24 Sep 2026 : apply the vendor's fix or mitigations to GS1900-48HPv2 firmware now.
Data as of 22 Sep 2026, 12:02 UTC
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 16 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: evidence found.
Listed in CISA KEV 97 days after disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by Zyxel Corporation
, 49 days before disclosure
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 40 minutes after disclosure
Added to CISA KEV (opens in a new tab)
exploitation confirmed
, 97 days after disclosure
KEV remediation due
US federal deadline
, 100 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| ZyxelGS1900-48HPv2 firmware | Affected
| Fixed in– |
| ZyxelGS1900-8 firmware | Affected
| Fixed in– |
| ZyxelGS1900-8HP firmware | Affected
| Fixed in– |
| ZyxelGS1900-10HP firmware | Affected
| Fixed in– |
| ZyxelGS1900-16 firmware | Affected
| Fixed in– |
| ZyxelGS1900-24 firmware | Affected
| Fixed in– |
AI-suggested
ZyXEL released official security updates in June 2026 that patch the vulnerability in ten GS1900 switch models. Organizations should apply these patches immediately. The US CISA mandates federal agencies to patch within three days. Devices should also be audited to replace factory default credentials with strong, unique passwords to reduce risk of further compromise. No additional mitigation is indicated beyond patching and credential management.
Description
A stack-based buffer overflow vulnerability (CVE-2026-7273) in ZyXEL GS1900 switches has been exploited by a Chinese threat actor to exfiltrate sensitive information from nearly 1,000 devices worldwide. The vulnerability allows unauthenticated OS command execution via crafted HTTP requests. ZyXEL released patches for ten GS1900 models in June 2026. The attacker used an obfuscated Python script targeting firmware versions 2.10 to 2.90, extracting hashed root credentials and configuration data. Over half of the compromised devices used factory default credentials, increasing risk. The US CISA added this vulnerability to its Known Exploited Vulnerabilities catalog, mandating patching within three days for federal agencies. The same threat actor also exploited other vulnerabilities in Ubiquiti devices and WordPress installations. The threat actor is suspected to be linked to the Red Heron group.