high Known exploitedREV. 01

CVE-2024-40891Zyxel DSL modems — command injection over telnet

The affected Zyxel modem firmware (VMG4325-B10A) runs operating system commands out of its management commands over telnet, for anyone already signed in. The device line is unsupported.

YOUR NEXT MOVE

Replace these modems — the line is unsupported and no fix is coming; until then stop the telnet service and keep them off routable networks.

Read the risk

THE VITAL STATS
CVSS score
8.8/ 10
CVSS v3.1
EPSS probability
22%
Likelihood of exploitation
Attack complexity
Low
Conditions needed to exploit
Known exploited
Yes — CISA KEV
CVE published
2025-02-04
Added to KEV
2025-02-11
Exploit published
Not recorded
Confidence
high
Kill chain
execution
MITRE ATT&CK
T1059
Severity
high

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attacker needsA valid login on the device's telnet service.

Behind the card

3 REFERENCES
Field-level provenanceTRACE THE SOURCES +

Which source supports each field, when it was retrieved, and who extracted it.

FieldsSourceRetrievedExtractorConfidence
cvss, exploitation.attack_complexity, exploitation.exploit_available, references, published_atnvd.nist.gov2026-09-24scrty-crds-pipeline/0.1high
exploitation.known_exploited, exploitation.kev_addedcisa.gov2026-09-24scrty-crds-pipeline/0.1high
epssapi.first.org2026-09-24scrty-crds-pipeline/0.1high
title, summary, severity, remediation, mitre_attack, kill_chain, recommended_action, confidence, tags, exploitation.prerequisitesnvd.nist.gov2026-09-24claude-codehigh

Printing history

THE RECORD
  1. r1Initial base card

First printing. This card has not been reprinted since publication.

crds:cve-2024-40891 · CRDS 0.1 · Issued 2026-09-24