CVE-2025-71384

Executive Summary

CVE-2025-71384 is an authenticated stack-based buffer overflow vulnerability affecting Dbit WIFI4 N300 1.0.0 wireless router devices. The flaw resides in the /api/addStaticDHCP endpoint and is triggered through an overly long value supplied in the comment field, allowing a user with administrative privileges on the local Wi-Fi network to corrupt the stack and achieve operating system command execution on the underlying device firmware. The impact is complete compromise of the affected router: attackers who already hold admin credentials (or obtain them through credential reuse, weak default passwords, or lateral movement within the wireless segment) can escalate from a management interface authenticated context to full OS-level command execution with the privileges of the vulnerable service.

Technical Analysis

The vulnerability class here is a classic stack-based buffer overflow (CWE-121). Per the available description, the /api/addStaticDHCP request handler on Dbit WIFI4 N300 1.0.0 firmware copies the contents of the comment parameter into a fixed-size stack buffer without adequate bounds checking. Because the comment field is intended to hold a short, human-readable description for a static DHCP reservation, the developers assumed input would remain small and did not implement length validation or safe copy primitives.

The attack surface is the device's local management API, exposed over the Wi-Fi network on which the device operates. The action described — adding a static DHCP entry — is normally a privileged administrative operation, so the attacker must already be authenticated as an administrator. That precondition is significant: this CVE is not a pre-authentication remote code execution flaw. It is a post-authentication privilege escalation from "administrative web user" to "OS command execution" on the device itself.

When the comment value exceeds the capacity of the destination stack buffer, contiguous stack memory — including saved registers and, most critically, the saved return address — is overwritten. By controlling the overflow contents, an attacker can redirect control flow within the vulnerable process. The public description explicitly states that the overflow is leveraged to execute OS commands, meaning the corrupting input is crafted to achieve command execution on the device rather than merely crashing it. The underlying firmware service is thus the execution context for any injected command.

Several important details are not present in the available intelligence: the exact size of the vulnerable buffer, the precise stack layout, the instruction set of the target hardware, and any memory-protection characteristics (ASLR, NX, stack canaries) of the firmware image. No public proof-of-concept, exploit code, or Nuclei template has been observed. Any precise offsets or gadget references would therefore be speculation and are deliberately omitted.

The CWE assignment (CWE-121, Stack-based Buffer Overflow) is consistent with the description. No CWE was provided in the source data; CWE-121 is applied here as the standard classification for this defect class. No CVSS score or vector was supplied by the source and none is fabricated — the vector listed in METADATA is an analytical estimate reflecting an adjacent-network attack (AV:A), high privileges required (PR:H), and full confidentiality/integrity/availability impact, appropriate for a post-authentication OS command execution flaw. It should be treated as provisional and not as a vendor or NVD-published score. EPSS has not yet scored this CVE by FIRST.org, so no exploitation-probability figure is asserted.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class and the limited description provided, and no function names, offsets, or parameters beyond those in the NVD text are asserted.

1. Reconnaissance / target identification. An attacker who has already joined the local Wi-Fi network — or who has network access to the device's management plane — identifies an exposed Dbit WIFI4 N300 management interface. Because exploitation requires administrator privileges, this phase includes obtaining valid admin credentials, for example via weak or default administrative passwords, credential reuse, or compromise of another host on the same wireless segment.

2. Triggering the flaw class. Authenticated as administrator, the attacker invokes the /api/addStaticDHCP operation with a comment field whose value is longer than the fixed-size stack buffer it is copied into. The length violation is the sole trigger; no malformed protocol framing or authentication bypass is required beyond valid credentials.

3. Payload / control-flow hijack. The overflow overwrites adjacent stack memory, including control data such as the saved return address. The attacker shapes the overwrite so that, instead of a simple crash, execution is redirected to attacker-influenced content. Per the description, the end result is execution of OS commands on the device.

4. Post-exploitation impact. Successful exploitation yields command execution at the privilege level of the vulnerable firmware service. From there, an attacker operating on the local network can use the router as a foothold: altering DNS settings or routing, intercepting or redirecting traffic traversing the device, establishing persistence, and pivoting deeper into the internal network. Because the device is a network edge component, compromise can affect every client that relies on it for connectivity.

Two constraints bound the real-world risk. First, the attacker must be on the local Wi-Fi network — this is not remotely exploitable from the internet. Second, administrative credentials are a hard precondition. As a result, the most realistic exploitation paths are malicious or compromised insiders on the wireless segment, and attackers who have already achieved a foothold and are escalating to control the network's routing and DNS.

Impact Assessment

The vulnerability is a full-integrity, full-availability, full-confidentiality compromise of the affected device once the preconditions are met. An attacker with OS command execution on a Wi-Fi router controls the chokepoint through which all connected clients communicate: traffic can be redirected, credentials harvested via manipulated DNS, sessions hijacked, and the device repurposed as a persistent platform for further attacks. In an enterprise context, a compromised WIFI4 N300 serving an office, branch, guest network, or retail site grants that attacker positions to attack every downstream host.

The blast radius is bounded by the authentication precondition and the local-network requirement. This is an adjacent-network, high-privilege attack, which tempers its severity relative to a pre-auth internet-facing RCE — but it materially raises the stakes for any environment where administrative credentials to the device are weak, shared, or obtainable, and for any environment where an attacker has already established an internal foothold. In IoT-heavy or small-office deployments, such routers are frequently left on default credentials and rarely monitored, making the preconditions easy to satisfy in practice.

Because the device is unpatched (patch confidence 0/4, no vendor fix, no workarounds published) and the CVE carries no CVSS score from the source, no standardized severity benchmark is available. Practitioners should treat the flaw as high severity on the basis of demonstrated OS command execution, while recognizing that the attack surface is limited to the local Wi-Fi network and authenticated operators. Absent exploit-in-the-wild evidence — none is reported here, and CISA KEV does not list this CVE — current risk is driven by exposure and credential hygiene rather than active campaigns.

Detection Guidance

Sigma Rule

title: Dbit WIFI4 N300 Stack Overflow via addStaticDHCP comment Field
id: 8f2c1a44-9b7e-4d3e-a1c2-7e5f0d9b2c31
status: experimental
description: Detects oversized comment values submitted to the /api/addStaticDHCP endpoint of Dbit WIFI4 N300 1.0.0, consistent with CVE-2025-71384 stack-based buffer overflow.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2025-71384
author: valtersit.com
date: 2025-01-01
logsource:
  category: webserver
  product: generic
detection:
  selection_endpoint:
    cs-uri-stem|contains: '/api/addStaticDHCP'
  selection_method:
    cs-method: 'POST'
  selection_oversized:
    cs-uri-query|contains|any:
      - 'comment='
    sc-bytes|gte: 4096
  condition: selection_endpoint and selection_method and selection_oversized
fields:
  - c-ip
  - cs-uri-stem
  - cs-uri-query
falsepositives:
  - Legitimate administrative use with unusually long descriptive comments
level: high

YARA Rule

rule CVE_2025_71384_Dbit_addStaticDHCP_Overflow
{
    meta:
        description = "Detects HTTP requests abusing the comment parameter of /api/addStaticDHCP on Dbit WIFI4 N300 1.0.0 (CVE-2025-71384)"
        reference   = "https://nvd.nist.gov/vuln/detail/CVE-2025-71384"
        author      = "valtersit.com"
        date        = "2025-01-01"
        severity    = "high"

    strings:
        $endpoint = "/api/addStaticDHCP" ascii nocase wide
        $comment  = "comment=" ascii nocase wide
        $http     = "HTTP/1." ascii
        $post     = "POST " ascii

    condition:
        uint16(0) == 0x4854 or
        (any of ($http, $post)) and $endpoint and $comment and filesize > 1KB
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2025-71384 Dbit WIFI4 N300 addStaticDHCP comment buffer overflow attempt"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/api/addStaticDHCP"; http.request_body; content:"comment="; pcre:"/comment=[^&]{512,}/i"; threshold:type limit, track by_src, count 1, seconds 60; classtype:attempted-admin; reference:cve,2025-71384; reference:url,nvd.nist.gov/vuln/detail/CVE-2025-71384; sid:202571384; rev:1;)

Elastic Detection

http.request.method == "POST" and
url.path == "/api/addStaticDHCP" and
length(http.request.body.content) > 4096

Splunk SPL Query

index=web OR index=proxy
| search uri_path="/api/addStaticDHCP" http_method="POST"
| eval comment_len = len(coalesce(form_data, request_body, ""))
| where comment_len > 4096
| stats count min(_time) as first_seen max(_time) as last_seen by src_ip, uri_path
| convert ctime(first_seen) ctime(last_seen)
| sort - count

Wazuh OSSEC Rule

<group name="web,attack,">
  <rule id="100784" level="12">
    <if_sid>31100</if_sid>
    <id>^/api/addStaticDHCP</id>
    <match>POST</match>
    <regex>comment=</regex>
    <description>CVE-2025-71384: Potential stack-based buffer overflow via /api/addStaticDHCP comment field on Dbit WIFI4 N300</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cve_2025_71384,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No vendor fix, no workarounds, and no patch evidence exist in any tracked source. The guidance below is therefore containment-oriented; it does not remediate the underlying code defect.

1. Immediate mitigations.

   • Treat the device's management interface as untrusted-side infrastructure: isolate the WIFI4 N300 management plane on a dedicated VLAN or SSID that is not reachable by general clients. Because the flaw is only reachable from the local Wi-Fi network, network segmentation directly reduces the attack surface.
   • Rotate all administrative credentials and eliminate default passwords; enforce unique, high-entropy admin secrets. Because exploitation requires administrative privileges, credential hygiene is the single highest-leverage control.
   • Where the device supports it, disable remote/unauthorized administrative access and restrict management to a trusted client or wired segment.
   • If the router is not essential, decommission or replace it. With no patch available, an unsupported device at a network chokepoint is an enduring liability.
   • Monitor for anomalous DNS or routing changes and for unexpected outbound connections from the device.

2. Patch/upgrade steps.

   • No patch is currently available for Dbit WIFI4 N300 1.0.0. Track future firmware releases and the NVD entry for CVE-2025-71384. Until a fixed firmware version is published, there is no upgrade path that removes the vulnerability — the device should be treated as unpatchable and removed from any trust path where possible.

3. Long-term hardening.

   • Adopt a vulnerability-management process that inventories IoT and small-office network gear, tracks end-of-support status, and replaces devices whose vendors do not ship security fixes.
   • Enforce network segmentation as a default architectural control for edge and IoT devices so that compromise of a single access point does not expose the broader estate.
   • Centralize authentication and logging for network devices, with alerting on the detections above.
   • Where feasible, procure network hardware with a documented security-fix commitment and a known CVSS/EPSS posture.

References

• NVD — CVE-2025-71384: https://nvd.nist.gov/vuln/detail/CVE-2025-71384
• MITRE CWE-121 — Stack-based Buffer Overflow: https://cwe.mitre.org/data/definitions/121.html
• MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
• CISA Known Exploited Vulnerabilities Catalog (CVE-2025-71384 is not listed): https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• FIRST EPSS (CVE-2025-71384 not yet scored): https://www.first.org/epss/

No threat actor campaigns and no exploit-in-the-wild evidence are associated with CVE-2025-71384 in the available intelligence. No public PoC, exploit code, or Nuclei template has been observed at the time of writing.