CVE-2025-13551 Overview
CVE-2025-13551 is a buffer overflow vulnerability affecting D-Link DIR-822K and DWR-M920 routers. The flaw resides in an unknown function within the /boafrm/formWanConfigSetup endpoint of the device web management interface. Attackers can trigger the overflow by manipulating the submit-url argument. The vulnerability is exploitable remotely, and a public exploit has been disclosed. The issue is classified under CWE-119, covering improper restriction of operations within the bounds of a memory buffer. Successful exploitation can compromise the confidentiality, integrity, and availability of the affected device.
Critical Impact
Remote attackers with low-privilege access can trigger a buffer overflow in the WAN configuration handler, potentially leading to arbitrary code execution or device compromise on affected D-Link routers.
Affected Products
- D-Link DIR-822K firmware version 1.00_20250513164613
- D-Link DWR-M920 firmware version 1.1.50 (hardware revision B2)
- D-Link DIR-822K and DWR-M920 router hardware
Discovery Timeline
- 2025-11-23 - CVE-2025-13551 published to NVD
- 2025-12-02 - Last updated in NVD database
Technical Details for CVE-2025-13551
Vulnerability Analysis
The vulnerability resides in the formWanConfigSetup handler accessed through the /boafrm/formWanConfigSetup URI on the embedded web server. This handler processes WAN configuration parameters submitted by authenticated users. The submit-url parameter is copied into a fixed-size stack buffer without proper length validation. An attacker who supplies an oversized value for submit-url overflows the buffer and corrupts adjacent memory. Because the flaw exists in a network-facing service, exploitation is possible over the network with low-privilege credentials. Successful exploitation can corrupt control flow on the embedded MIPS or ARM platforms used in these routers.
Root Cause
The root cause is missing bounds checking on user-supplied input written to a fixed-size buffer, consistent with CWE-119. The boa web server, common in D-Link consumer devices, hands form parameters directly to handler functions that use unsafe string operations such as strcpy or sprintf. Without input length validation, attacker-controlled data overwrites the stack frame, including saved return addresses.
Attack Vector
An attacker sends a crafted HTTP POST request to /boafrm/formWanConfigSetup containing an oversized submit-url parameter. Reaching the endpoint requires low-privilege authentication. Once the overflow occurs, the attacker can corrupt program state, cause a denial of service, or hijack execution flow to run arbitrary code on the device. Public proof-of-concept material has been referenced in GitHub Issue #35 and GitHub Issue #46.
No verified exploit code is reproduced here. Technical details are available in the referenced VulDB entry #333318.
Detection Methods for CVE-2025-13551
Indicators of Compromise
- HTTP POST requests to /boafrm/formWanConfigSetup containing unusually long submit-url parameter values
- Unexpected reboots, watchdog resets, or crashes of the router web management daemon
- New or unrecognized administrative sessions on affected D-Link DIR-822K or DWR-M920 devices
- Outbound connections from the router to unknown hosts following web interface access
Detection Strategies
- Inspect web server access logs on affected routers for requests targeting formWanConfigSetup with oversized parameters
- Deploy network intrusion detection signatures matching POST requests to /boafrm/formWanConfigSetup with submit-url payloads exceeding expected URL length limits
- Monitor for HTTP request bodies to the router management interface that exceed normal sizes
Monitoring Recommendations
- Forward router syslog and HTTP access logs to a centralized logging platform for retention and correlation
- Alert on repeated POST requests to /boafrm/ endpoints from a single source within short time windows
- Track router process restarts and configuration changes outside scheduled maintenance windows
How to Mitigate CVE-2025-13551
Immediate Actions Required
- Restrict access to the router web management interface to trusted internal networks only and disable WAN-side administration
- Change default and weak administrative credentials, since exploitation requires low-privilege authentication
- Audit recent administrative access logs on D-Link DIR-822K and DWR-M920 devices for suspicious activity
- Place affected devices behind network segmentation to limit lateral movement if compromised
Patch Information
No vendor patch has been published at the time of NVD disclosure. Refer to the D-Link Security Information portal for firmware updates. Customers should monitor vendor advisories and apply firmware updates as soon as they become available.
Workarounds
- Disable remote management on the WAN interface to prevent external exploitation attempts
- Apply access control lists restricting which internal hosts may reach the router admin interface
- Replace end-of-support or legacy D-Link hardware with currently supported devices if no patch is forthcoming
- Place the router behind an upstream firewall that filters HTTP traffic to management endpoints
# Example: restrict router admin interface access via upstream firewall (iptables)
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -s <trusted_mgmt_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -s <trusted_mgmt_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
