High Injection

CVE-2026-1459 — OS Command Injection in Zyxel Dx5401-b1 Firmware

A post-authentication command injection vulnerability in the TR-369 certificate download CGI program of the Zyxel VMG3625-T50B firmware versions through 5.50(ABPM.9.7)C0 could allow an authenticated attacker with administrator privileges to execute operating system (OS) commands on an affected device.

Published Feb 24, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Zyxel

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.9% (30-day exploitation probability)+9
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.92%

ahead of 59% of scored CVEs · Oct 14, 2026

Affects

Zyxel

Dx5401-b1 Firmware and 5 more

CVSS base

7.2

High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Zyxel Dx5401-b1 Firmware, Zyxel Emg3525-t50b Firmware, Zyxel Emg5523-t50b Firmware…).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Zyxel	Dx5401-b1 Firmware	≤ 5.17\(abyo.7.1\)c0	Vulnerable	NIST National Vulnerability Database
Zyxel	Emg3525-t50b Firmware	≤ 5.50\(abpm.9.7\)c0	Vulnerable	NIST National Vulnerability Database
Zyxel	Emg5523-t50b Firmware	≤ 5.50\(abpm.9.7\)c0	Vulnerable	NIST National Vulnerability Database
Zyxel	Vmg3625-t50b Firmware	≤ 5.50\(abpm.9.7\)c0	Vulnerable	NIST National Vulnerability Database
Zyxel	Vmg3625-t50b Firmware	version <= 5.50(ABPM.9.7)C0	Vulnerable	CVE Program (cve.org) e CISA ADP
Zyxel	Vmg3625-t50c Firmware	≤ 5.50\(abpm.9.7\)c0	Vulnerable	NIST National Vulnerability Database
Zyxel	Vmg8623-t50b Firmware	≤ 5.50\(abpm.9.7\)c0	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

High

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.2	CVSS 3.1	High	1.2	5.9	security@zyxel.com.tw via NIST National Vulnerability Database
7.2	CVSS 3.1	High	1.2	5.9	nvd@nist.gov via NIST National Vulnerability Database
7.2	CVSS 3.1	High	—	—	Zyxel via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-78 · OS Command Injection

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.92%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Look for parameters with command/query metacharacters and unexpected child processes of the service.

web/proxy/WAF logsnetwork IDS/IPSapplication logsendpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · zyxel/vmg3625-t50b firmware
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 7.2
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Feb 24, 2026 · Zyxel

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-nul
Vendor Advisory, vendor-advisory, NIST National Vulnerability Database

Elsewhere on this site

Zyxel
every CVE for this vendor

Injection
same class

CWE-78
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-0711 OS Command Injection in Zyxel Nr5307 Firmware Apr 28, 2026
High CVE-2026-1460 OS Command Injection in Zyxel Nebula Fwa70 Firmware Apr 28, 2026
Medium CVE-2025-11848 NULL Pointer Dereference in Zyxel Ex5601-t1 Firmware Feb 24, 2026
High CVE-2025-13943 OS Command Injection in Zyxel Ex5601-t1 Firmware Feb 24, 2026
Medium CVE-2025-11847 NULL Pointer Dereference in Zyxel Ex3510-b1 Firmware Feb 24, 2026
Medium CVE-2025-11846 NULL Pointer Dereference in Zyxel Lte3301-plus Firmware Feb 23, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-1459 is "OS Command Injection in Zyxel Dx5401-b1 Firmware", rated High. It affects Dx5401-b1 Firmware (Zyxel); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.2 describes technical severity. EPSS 0.92% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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