Zyxel DSL CPE OS Command Injection Vulnerability
Zyxel · DSL CPE Devices
Zyxel DSL CPE devices, specifically the VMG4325-B10A running firmware 1.00(AAFR.4)C0_20170615, contain a command injection flaw in the management commands. The flaw is a legacy issue in an unsupported product. An authenticated attacker can run operating system commands on the affected device via Telnet, so valid credentials are required and the attacker must be able to reach the device's Telnet service.
**UNSUPPORTED WHEN ASSIGNED** A post-authentication command injection vulnerability in the management commands 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 via Telnet.
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 3/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 7 days before it was disclosed. Public exploit code (PoC-in-GitHub) appeared 18 months after disclosure.
- First seen exploitedVulnCheck KEV evidence7 days before
- Disclosedday 0
- Added to CISA KEVEU database agrees+7 days
- Public exploit codePoC-in-GitHub+18 mo
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order 2Privilege EscalationTA0004
Zyxel CPE devices contain a Telnet interface that fails to properly sanitize input containing special characters, which facilitates code execution that can lead to data exfiltration, network infiltration, and total system compromise.
ExfiltrationTA0010
Detection
0 rules for this CVE · 37 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2024-40891 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Process InjectionT105537 general rules
- Antivirus PrinterNightmare CVE-2021-34527 Exploit Detectioncriticalstable
- Potential Dridex Activitycriticalstable
- CobaltStrike Named Pipecriticaltest
- CobaltStrike Named Pipe Pattern Regexcriticaltest
- HackTool - DInjector PowerShell Cradle Executioncriticaltest
- Malicious Named Pipe Createdcriticaltest
- RedSun - Named Pipe Createdcriticalexperimental
- RedSun - TieringEngineService.exe Detected as EICAR Test Filecriticalexperimental
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 30, 202629 Oct 2026
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
- 44 more on OTX