CVE-2025-13548 Overview
CVE-2025-13548 is a buffer overflow vulnerability affecting D-Link DIR-822K and DWR-M920 routers. The flaw resides in the /boafrm/formFirewallAdv handler, where the submit-url parameter is processed without proper bounds checking. An authenticated remote attacker can manipulate this argument to overflow a fixed-size buffer in the boa web server process. The vulnerability has been publicly disclosed, and exploit details are available through third-party CVE tracking sources. The affected firmware versions include DIR-822K 1.00_20250513164613 and DWR-M920 1.1.50. The weakness is categorized under [CWE-119], improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers with low privileges can trigger memory corruption on affected D-Link routers, potentially leading to denial of service or arbitrary code execution on the device.
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 running the affected firmware
Discovery Timeline
- 2025-11-23 - CVE-2025-13548 published to NVD
- 2025-12-02 - Last updated in NVD database
Technical Details for CVE-2025-13548
Vulnerability Analysis
The vulnerability exists in the firewall configuration handler exposed by the embedded boa web server on affected D-Link devices. When a client submits a POST request to /boafrm/formFirewallAdv, the handler reads the submit-url form parameter and copies it into a fixed-size stack or heap buffer. The implementation does not validate the length of the supplied value before the copy operation. Supplying an overly long submit-url string corrupts adjacent memory regions. Depending on the buffer location, this can overwrite saved return addresses, function pointers, or heap metadata. The result is a process crash at minimum, with the potential for control-flow hijacking on devices lacking robust exploit mitigations.
Root Cause
The root cause is the absence of length validation and the use of unsafe string-handling primitives such as strcpy or sprintf in the formFirewallAdv request handler. Consumer-grade router firmware frequently lacks stack canaries, address space layout randomization (ASLR), and non-executable memory enforcement. These missing mitigations make a buffer overflow in a network-facing service directly exploitable for code execution.
Attack Vector
An attacker reaches the vulnerable endpoint over the network. The CVSS vector indicates that low-level authentication to the router web interface is required. Once authenticated, the attacker sends a crafted HTTP request containing an oversized submit-url argument to /boafrm/formFirewallAdv. If the router web interface is exposed to the WAN or accessible from an attacker-controlled internal host, the flaw can be triggered remotely. Successful exploitation undermines the confidentiality, integrity, and availability of the device, which sits at the network perimeter.
Further technical details and proof-of-concept discussion are available in the GitHub CVE Issue Discussion and VulDB entry #333315.
Detection Methods for CVE-2025-13548
Indicators of Compromise
- HTTP POST requests to /boafrm/formFirewallAdv containing unusually long submit-url parameter values, typically exceeding several hundred bytes.
- Unexpected reboots, crashes, or web interface unavailability on DIR-822K or DWR-M920 devices following inbound HTTP traffic.
- Outbound connections from the router to unknown hosts, which may indicate post-exploitation activity such as botnet enrollment.
Detection Strategies
- Inspect web server access logs on the router, if available, for repeated requests targeting formFirewallAdv with oversized payloads.
- Deploy network intrusion detection signatures that flag HTTP request bodies containing submit-url fields exceeding a defined length threshold.
- Monitor router management interfaces for unauthenticated or brute-force login attempts that may precede exploitation of this authenticated flaw.
Monitoring Recommendations
- Collect and centralize syslog data from affected D-Link devices to enable retrospective analysis of crashes and request patterns.
- Alert on devices that fail to respond to scheduled health checks, as silent crashes are a common symptom of overflow exploitation.
- Track configuration drift on routers to detect unauthorized changes to firewall, DNS, or routing settings that follow successful exploitation.
How to Mitigate CVE-2025-13548
Immediate Actions Required
- Restrict access to the router web management interface so that only trusted internal hosts can reach /boafrm/formFirewallAdv.
- Disable WAN-side administration on DIR-822K and DWR-M920 devices to remove direct internet exposure of the vulnerable endpoint.
- Rotate administrator credentials on affected devices, since the attack requires authentication and credential reuse increases risk.
- Audit the device inventory to identify all DIR-822K units and DWR-M920 hardware revision B2 units running the affected firmware.
Patch Information
As of publication, no fixed firmware version has been listed in the NVD record for CVE-2025-13548. Administrators should monitor D-Link Security Resources for vendor advisories and updated firmware releases addressing the formFirewallAdv buffer overflow. Apply firmware updates promptly after vendor release and validate via checksum prior to deployment.
Workarounds
- Place affected routers behind an upstream firewall that filters HTTP and HTTPS traffic to the management interface from untrusted networks.
- Segment IoT and management networks so that only a dedicated administrative VLAN can reach router configuration endpoints.
- Consider replacing end-of-support D-Link consumer hardware with actively maintained platforms if no firmware fix is released.
- Disable remote management features and UPnP where business requirements permit, reducing the exposed attack surface.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
