CVE Alert: CVE-2025-9938 – D-Link – DI-8400
CVE-2025-9938
A weakness has been identified in D-Link DI-8400 16.07.26A1. The affected element is the function yyxz_dlink_asp of the file /yyxz.asp. This manipulation of the argument ID causes stack-based buffer overflow. It is possible to initiate the attack remotely. The exploit has been made available to the public and could be exploited.
AI Summary Analysis
Risk verdict
High risk: remote code execution is possible with no user interaction, and a public PoC exists for exploitation.
Why this matters
An attacker could take control of the device from the network edge, enabling persistence, data exfiltration, or network pivot to adjacent assets. With no user interaction required and network-level access, exposed deployments are attractive targets for opportunistic and potentially coordinated campaigns.
Most likely attack path
An attacker would probe the vulnerable endpoint, sending crafted input to trigger a stack-based overflow. The vulnerability’s CVSS profile (remote, low-privilege access, high impact) plus the PoC suggests automated or semi-automated attempts could succeed, leading to immediate device compromise and possible lateral movement from the edge to internal networks.
Who is most exposed
Networks with publicly reachable edge devices or lacking strict remote-management controls are most at risk; typical exposure includes internet-facing management interfaces or devices deployed in SMB/branch networks with outdated firmware.
Detection ideas
- Unexpected traffic targeting the vulnerable endpoint, especially crafted parameters or overflow payloads.
- Crash events, reboot loops, or unusual memory/CPU spikes on the device.
- Logs showing failed/blocked overflow attempts; signature hits for known PoC indicators.
- Anomalous outbound connections from the device to internal or external hosts following access attempts.
- Unusual user-interface or admin-session activity tied to remote management.
Mitigation and prioritisation
- Apply the latest firmware update or vendor-supplied patch immediately; verify integrity before rollout.
- Restrict remote management: disable internet exposure; enforce VPN-only access or strict ACLs.
- Implement network segmentation and firewall rules to isolate edge devices from critical systems.
- Enable enhanced logging, forward to a SIEM, and tune for overflow- or PoC-related indicators.
- Plan a change window for patch deployment; test in a staging environment before production.
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