CVE-2024-9908: D-Link DIR-619L Buffer Overflow Vulnerability

CVE-2024-9908 Overview

CVE-2024-9908 is a buffer overflow vulnerability affecting the D-Link DIR-619L B1 router running firmware version 2.06. The flaw resides in the formSetMACFilter function handled by the /goform/formSetMACFilter endpoint. An attacker on an adjacent network can manipulate the curTime argument to trigger a buffer overflow in the router's HTTP request handler. The exploit has been publicly disclosed, increasing the risk of opportunistic abuse against exposed devices. The vulnerability is classified under CWE-120, Buffer Copy without Checking Size of Input.

Critical Impact
Authenticated adjacent-network attackers can trigger a buffer overflow in the router web management interface, potentially crashing the device or corrupting memory used by the HTTP daemon.

Affected Products

D-Link DIR-619L B1 hardware revision
D-Link DIR-619L firmware version 2.06b1
Deployments exposing the /goform/formSetMACFilter endpoint on adjacent networks

Discovery Timeline

2024-10-13 - CVE-2024-9908 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-9908

Vulnerability Analysis

The DIR-619L web management interface exposes the formSetMACFilter handler under /goform/formSetMACFilter. This handler processes MAC address filtering configuration requests submitted by authenticated users of the administrative interface. The curTime argument, transmitted as part of the request body, is copied into a fixed-size stack buffer without validating input length.

By supplying an oversized curTime value, an attacker overwrites adjacent stack memory. This can crash the HTTP daemon, corrupt saved return addresses, or influence subsequent control flow within the process. Because the device is a consumer-grade IoT router with limited exploit mitigations, memory corruption on the MIPS-based platform can escalate beyond a denial of service in some configurations.

The EPSS score of 2.589% places this issue in the 83.8th percentile, reflecting elevated interest relative to typical CVEs. See the public write-up on GitHub and the VulDB entry #280236 for additional technical detail.

Root Cause

The formSetMACFilter function does not enforce bounds checking when copying the curTime argument into a stack-allocated buffer. This missing length validation is the classic pattern captured by CWE-120. The router firmware also lacks stack canaries and hardened compiler flags common in modern platforms, which increases the exploitability of the overflow.

Attack Vector

The attacker must reach the router's HTTP management interface, typically only exposed to the local LAN or Wi-Fi segment. The attacker submits a crafted HTTP POST request to /goform/formSetMACFilter with an oversized curTime parameter. Because valid session credentials for the router are required, the practical scenario involves an attacker already positioned on the trusted network or leveraging default and reused administrator credentials.

No verified proof-of-concept code is included here. The referenced GitHub advisory documents the vulnerable parameter and endpoint.

Detection Methods for CVE-2024-9908

Indicators of Compromise

Unexpected reboots or watchdog resets of DIR-619L devices following administrative traffic
HTTP POST requests to /goform/formSetMACFilter containing abnormally long curTime values
Web management daemon crashes recorded in router system logs
New or unexplained MAC filter configuration entries appearing without administrator action

Detection Strategies

Inspect LAN-side HTTP traffic for requests targeting /goform/formSetMACFilter with parameter lengths exceeding expected bounds
Deploy network intrusion detection signatures matching oversized curTime fields in DIR-619L admin traffic
Correlate router availability alerts with recent administrative HTTP sessions to identify potential exploitation attempts

Monitoring Recommendations

Enable syslog forwarding from the router to a central log collector for continuous availability monitoring
Track authentication events to the DIR-619L web interface and alert on unusual source addresses
Monitor for unauthorized devices on the LAN or Wi-Fi network that could serve as an adjacent-network foothold

How to Mitigate CVE-2024-9908

Immediate Actions Required

Restrict access to the router administration interface to trusted management hosts only
Disable remote management and ensure the HTTP admin service is not exposed on the WAN interface
Change default administrator credentials and enforce strong, unique passwords
Segment guest and untrusted devices onto isolated VLANs or SSIDs to reduce adjacent-network exposure

Patch Information

No vendor patch has been published in the referenced advisories at the time of writing. The DIR-619L B1 is a legacy consumer router, and organizations should consult the D-Link official website for end-of-life and firmware update status. Where updates are unavailable, plan migration to a supported router platform.

Workarounds

Replace end-of-life DIR-619L hardware with a currently supported and patched router model
Place the router behind an upstream firewall that blocks direct access to /goform/ endpoints from untrusted segments
Disable Wi-Fi guest networks or restrict them with client isolation to limit adjacent-network reach to the admin interface
Apply MAC filtering and management-VLAN restrictions so only designated administrator workstations can reach the web UI

bash

# Example: block access to the DIR-619L admin interface from a guest VLAN
# on an upstream Linux gateway (adjust interface and subnet values)
iptables -A FORWARD -i guest0 -d 192.168.0.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -i guest0 -d 192.168.0.1 -p tcp --dport 443 -j DROP