CVE-2026-4584 Overview
A cryptographic vulnerability has been identified in the Shenzhen HCC Technology MPOS M6 PLUS point-of-sale terminal running firmware version 1V.31-N. The flaw affects the Cardholder Data Handler component, which transmits sensitive payment card information in cleartext over the local network. This weakness in the device's cryptographic implementation could allow an attacker with adjacent network access to intercept cardholder data during payment transactions.
Critical Impact
Sensitive cardholder data including payment card information may be exposed to attackers with local network access, potentially leading to financial fraud and PCI-DSS compliance violations.
Affected Products
- Shenzhen HCC Technology MPOS M6 PLUS firmware version 1V.31-N
- Cardholder Data Handler component
Discovery Timeline
- 2026-03-23 - CVE-2026-4584 published to NVD
- 2026-03-23 - Last updated in NVD database
Technical Details for CVE-2026-4584
Vulnerability Analysis
This vulnerability falls under CWE-310 (Cryptographic Issues), indicating a fundamental weakness in how the MPOS device handles sensitive payment data. The Cardholder Data Handler component fails to properly encrypt cardholder information before transmission over the network. While the attack requires adjacent network access and exhibits high complexity (making exploitation difficult), successful interception would expose sensitive payment card data.
The vulnerability is particularly concerning in retail and hospitality environments where MPOS terminals are commonly deployed on shared local networks. An attacker positioned on the same network segment could potentially capture payment card data transmitted by the vulnerable device.
Root Cause
The root cause stems from improper cryptographic implementation within the Cardholder Data Handler component. The device transmits sensitive cardholder data in cleartext rather than using appropriate encryption protocols. This represents a violation of PCI-DSS requirements for protecting cardholder data in transit, specifically Requirement 4 which mandates encryption of cardholder data across open, public networks.
Attack Vector
The attack vector requires the adversary to have access to the adjacent network where the MPOS terminal operates. From this position, an attacker could employ network sniffing techniques to capture unencrypted traffic containing cardholder data. The high attack complexity noted in the vulnerability assessment indicates that successful exploitation requires specific conditions to be met, including proper network positioning and timing of the interception during active payment transactions.
The attacker would need to:
- Gain access to the same network segment as the MPOS device
- Deploy network traffic capture tools (such as packet analyzers)
- Filter captured traffic for payment transaction data
- Extract cardholder information from the cleartext transmissions
Detection Methods for CVE-2026-4584
Indicators of Compromise
- Unencrypted network traffic on ports commonly used for payment processing
- Network traffic containing plaintext payment card data patterns (PAN, CVV, expiration dates)
- Unusual network reconnaissance activity targeting MPOS device segments
- Evidence of packet capture tools or ARP spoofing on the local network
Detection Strategies
- Implement network traffic analysis to identify cleartext transmission of sensitive data patterns
- Deploy intrusion detection systems (IDS) with rules to detect unencrypted PCI data in network flows
- Monitor for ARP spoofing or other man-in-the-middle positioning attacks on network segments containing MPOS terminals
- Conduct regular network vulnerability assessments focusing on payment terminal communications
Monitoring Recommendations
- Enable logging on network infrastructure devices to capture traffic patterns to and from MPOS terminals
- Implement Data Loss Prevention (DLP) solutions configured to detect cardholder data in network traffic
- Establish baseline network behavior for MPOS devices and alert on anomalies
- Review network captures periodically for evidence of cleartext sensitive data transmission
How to Mitigate CVE-2026-4584
Immediate Actions Required
- Isolate affected MPOS M6 PLUS devices on a dedicated network segment with strict access controls
- Implement network-level encryption (such as IPsec or VPN tunnels) for traffic to and from the vulnerable devices
- Conduct a review of all payment processing infrastructure for similar cleartext transmission vulnerabilities
- Consider replacing vulnerable devices with PCI-DSS compliant alternatives if vendor patch is unavailable
Patch Information
No vendor patch is currently available. According to the vulnerability disclosure, the vendor (Shenzhen HCC Technology) was contacted about this issue but did not respond. Organizations using the affected MPOS M6 PLUS 1V.31-N firmware should implement compensating controls until a patch becomes available, or consider device replacement.
For additional technical details, refer to the GitHub CVE-3 Data Exposure Documentation and VulDB #352421.
Workarounds
- Deploy a VPN or encrypted tunnel for all MPOS device communications
- Segment the network to isolate MPOS terminals from general network traffic
- Implement 802.1X network access control to restrict who can connect to the MPOS network segment
- Use a payment gateway that enforces transport-layer encryption regardless of endpoint capabilities
# Example: Network segmentation using VLAN isolation for MPOS devices
# Configure VLAN for payment terminals (example Cisco IOS)
interface Vlan100
description MPOS_PAYMENT_TERMINALS_ISOLATED
ip address 10.100.100.1 255.255.255.0
no ip proxy-arp
!
# Apply ACL to restrict inter-VLAN traffic
ip access-list extended MPOS_RESTRICT
permit tcp 10.100.100.0 0.0.0.255 host 10.200.1.10 eq 443
deny ip any any log
!
interface Vlan100
ip access-group MPOS_RESTRICT in
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