How to check if you are exposed to CVE-2024-40890
- Find every Zyxel DSL CPE Devices system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
- Compare each version with the fixed versions in the vendor advisory below. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
- Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2024-40890.
US federal agencies had to fix this by 2025-03-04. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.
Timeline
- · Added to CISA's Known Exploited Vulnerabilities catalog
- · Fix-by date for US federal agencies, passed 607 days ago
Vendor advisories and fixes
- https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-command-injection-and-insecure-default-credentials-vulnerabilities-in-certain-legacy-dsl-cpe-02-04-2025
- https://www.zyxel.com/service-provider/global/en/security-advisories/zyxel-security-advisory-command-injection-insecure-in-certain-legacy-dsl-cpe-02-04-2025
Weakness type
More exploited Zyxel vulnerabilities
CISA lists 13 exploited Zyxel vulnerabilities. The closest matches:
- CVE-2024-40891Zyxel DSL CPE OS Command Injection VulnerabilityAdded 2025-02-11
- CVE-2026-7273Zyxel GS1900 Series Switches Stack-Based Buffer Overflow VulnerabilityAdded 2026-09-21
- CVE-2024-11667Zyxel Multiple Firewalls Path Traversal VulnerabilityAdded 2024-12-03
- CVE-2017-6884Zyxel EMG2926 Routers Command Injection VulnerabilityAdded 2023-09-18
- CVE-2017-18368Zyxel P660HN-T1A Routers Command Injection VulnerabilityAdded 2023-08-07
- CVE-2023-27992Zyxel Multiple NAS Devices Command Injection VulnerabilityAdded 2023-06-23
- CVE-2023-33010Zyxel Multiple Firewalls Buffer Overflow VulnerabilityAdded 2023-06-05
- CVE-2023-33009Zyxel Multiple Firewalls Buffer Overflow VulnerabilityAdded 2023-06-05
Keep going
Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.