Threats / Zyxel / CVE-2024-40890
CVE-2024-40890
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Zyxel DSL CPE Devices vulnerability
Zyxel DSL CPE devices contain a post-authentication command injection vulnerability allowing authenticated attackers to execute arbitrary OS commands via crafted HTTP requests.
Verdict
Today item — known-exploited.
An authenticated attacker can inject OS commands through the CGI program to achieve code execution on affected Zyxel DSL CPE devices. This vulnerability is actively exploited in the wild and requires valid credentials to trigger.
CISA KEV Yes · 2025-02-115EPSS 0.22251 (verify live)6CVSS 8.83CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
3 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-02-11).
Probability (EPSS)
EPSS 0.22251 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) · Affected: Zyxel, DSL CPE Devices. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-78 OS Command Injection — weakness family: Injection.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 7 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I obtain valid credentials for the DSL CPE device through phishing, credential stuffing, or default credentials.
Business
Compromised device credentials enable unauthorized access to customer network infrastructure.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I craft a malicious HTTP request containing OS command injection payloads and send it to the vulnerable CGI program.
Business
The device becomes a pivot point for lateral movement into customer networks and IoT environments.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary commands with the privileges of the CGI process to install backdoors, modify configurations, or exfiltrate data.
Business
Customer network integrity is compromised, enabling data theft, service disruption, and persistent unauthorized access.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05