OS command injection
Input changes a command that the server runs through its operating system.
CWE-78 · CISA KEV; NVD record: security@zyxel.com.tw
Reading and practice labs · Free account for labs. Basic HTTP knowledge; some labs use Burp Suite.
Exploited. On CISA's list since 2025-02-11.
Zyxel DSL CPE OS Command Injection Vulnerability
CVE-2024-40890 · Zyxel DSL CPE Devices · Published 2025-02-04
How bad would it be?
8.8 out of 10
CVSS rates it high.
How likely is it to be used?
21%
Estimated chance of exploitation in the next 30 days, higher than 97% of all scored flaws (EPSS, 2026-10-29).
Is it already being used?
Yes
CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 605 days ago (2025-03-04).
What CISA says to do
The impacted product could be end-of-life (EoL) and/or end-of-service (EoS). Users should discontinue product utilization if a current mitigation is unavailable.
Multiple Zyxel DSL CPE devices contain a post-authentication command injection vulnerability in the CGI program that could allow an authenticated attacker to execute OS commands via a crafted HTTP request.
What the flaw is
**UNSUPPORTED WHEN ASSIGNED** A post-authentication command injection vulnerability in the CGI program of the legacy DSL CPE Zyxel VMG4325-B10A firmware version 1.00(AAFR.4)C0_20170615 could allow an authenticated attacker to execute operating system (OS) commands on an affected device by sending a crafted HTTP POST request.
From the NVD.
Fixes and advisories
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Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.