CVE-2022-37055: D-Link Routers -- Buffer Overflow RCE

Background

D-Link is one of the world’s largest manufacturers of consumer and small business networking equipment. Many D-Link router models have reached end-of-life (EoL) or end-of-support (EoS) status, meaning D-Link no longer releases security patches for them. These devices remain widely deployed in homes and small offices, creating a persistent and largely unpatched attack surface.

CVE-2022-37055 describes a buffer overflow vulnerability in D-Link router firmware with high impact across all three pillars of the CIA triad: confidentiality, integrity, and availability. This class of vulnerability can enable unauthenticated remote code execution, turning affected routers into persistent footholds for botnet operators, cryptominers, or nation-state actors. CISA added this to the KEV catalog on 2025-12-08.

The device’s position at the network perimeter makes compromise especially dangerous, as attackers gain full visibility into and control over all traffic traversing the router.

Technical Mechanism

The vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input). In typical D-Link router firmware, CGI-based web interfaces process HTTP request parameters by copying them into fixed-size stack or heap buffers without proper length validation.

// Vulnerable pattern in router CGI handler (simplified)
void handle_request(char *input) {
    char buffer[256];       // fixed-size stack buffer
    strcpy(buffer, input);  // CWE-120: no bounds check
    // Overflow overwrites return address or adjacent variables
    process_value(buffer);
}

An attacker crafting an oversized HTTP request to the vulnerable CGI endpoint can overwrite the stack return address, redirecting execution to attacker-controlled shellcode or ROP gadgets within the firmware.

Real-World Exploitation Evidence

Buffer overflow vulnerabilities in D-Link routers have a long history of exploitation by Mirai botnet variants and their successors. The CISA KEV listing on 2025-12-08 confirms this specific vulnerability is being actively exploited. Compromised D-Link routers are typically enrolled in DDoS botnets, used as proxy nodes for criminal infrastructure, or leveraged for lateral movement into connected networks. Given the EoL status of many affected models, no official patch is expected.

Impact Assessment

• Unauthenticated remote code execution on the router
• Full network traffic interception and manipulation (MITM)
• Persistent access via firmware modification
• Enrollment in botnet for DDoS, proxy abuse, or cryptomining
• Pivot point to compromise devices on the local network

Affected Versions

Remediation Steps

1. Check D-Link’s security advisory for whether your specific model is supported.
2. For supported models: apply the latest firmware update immediately.
3. For EoL/EoS models: replace the device — no patches will be issued.
4. Disable remote management interfaces (WAN-side web UI, SSH) if not required.
5. Place the router behind an upstream firewall if replacement is delayed.
6. Monitor for unexpected outbound connections or traffic anomalies.

Detection Guidance

Log Sources: Network flow data, IDS/IPS alerts, upstream firewall logs.

IOCs: Oversized HTTP requests to router CGI endpoints; unusual outbound connections from router IP to C2 infrastructure; unexpected firmware changes.

Suricata rule:

alert http $EXTERNAL_NET any -> $HOME_NET any (
  msg:"ET EXPLOIT D-Link Router Buffer Overflow Attempt CVE-2022-37055";
  flow:established,to_server;
  content:"POST"; http_method;
  content:".cgi"; http_uri;
  dsize:>1024;
  classtype:attempted-admin;
  sid:2099003; rev:1;
)

Timeline

References

• NVD — CVE-2022-37055
• CISA KEV — CVE-2022-37055
• D-Link Security Advisory — CVE-2022-37055