CVE-2026-7854
Buffer Overflow in D-Link DI-8100 Router
Publication date: 2026-05-05
Last updated on: 2026-05-06
Assigner: VulDB
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| dlink | di-8100_firmware | 16.07.26a1 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-119 | The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data. |
| CWE-120 | The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
CVE-2026-7854 is a critical stack-based buffer overflow vulnerability found in the D-Link DI-8100 Gigabit Router firmware version 16.07.26A1. The flaw exists in the url_rule_asp handler function, which improperly uses the sprintf function to concatenate user-supplied HTTP POST parameters into a fixed-size stack buffer of only 8 bytes.
This improper handling allows remote attackers, either authenticated or unauthenticated, to corrupt stack memory by sending a specially crafted HTTP POST request to the /url_rule.asp endpoint. This can cause the router's httpd service to crash, resulting in a denial-of-service (DoS) condition and making the router's web interface inaccessible until a physical reboot.
If an attacker gains control over the instruction pointer through this overflow, it could lead to remote code execution (RCE), allowing full device compromise, traffic interception, or recruitment into a botnet.
How can this vulnerability impact me? :
This vulnerability can severely impact the availability and security of your D-Link DI-8100 router. An attacker can cause a denial-of-service (DoS) by crashing the router's web interface, making it inaccessible until manually rebooted.
More critically, if exploited further, it could allow an attacker to execute arbitrary code remotely, leading to full device compromise. This could result in interception of your network traffic, unauthorized control over your device, or your router being used as part of a botnet.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by monitoring for unusual HTTP POST requests sent to the /url_rule.asp endpoint of the D-Link DI-8100 router. Specifically, crafted POST requests with excessively large payloads in the 'name' parameter (such as 200,000 'A' characters) are indicative of an exploit attempt.
To detect potential exploitation attempts on your network, you can use network traffic inspection tools or web server logs to identify large or malformed POST requests targeting /url_rule.asp.
Example commands to detect such activity might include:
- Using tcpdump to capture HTTP POST requests to /url_rule.asp: tcpdump -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep 'POST /url_rule.asp'
- Using grep on web server logs to find large POST requests to /url_rule.asp: grep '/url_rule.asp' /var/log/httpd/access_log | awk '{print $0, length($0)}' | sort -kNF,NR -n
- Using a Python script or custom IDS rule to detect unusually large 'name' parameter values in POST requests.
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation steps include restricting access to the router's web interface to trusted networks or IP addresses to prevent remote exploitation.
If possible, disable or restrict the URL filtering feature that uses the /url_rule.asp handler until a patch or firmware update is available.
Monitor the device for crashes or unavailability of the httpd service, which may indicate exploitation attempts.
Apply any available firmware updates or patches from the vendor addressing this vulnerability as soon as they are released.
Consider implementing network-level protections such as web application firewalls (WAF) or intrusion detection/prevention systems (IDS/IPS) to block malicious POST requests targeting /url_rule.asp.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The vulnerability in the D-Link DI-8100 router allows remote attackers to cause denial-of-service or potentially execute remote code, leading to full device compromise. Such a compromise could result in unauthorized access to network traffic or device control, which may impact the confidentiality, integrity, and availability of data handled by the device.
While the provided information does not explicitly mention compliance with standards like GDPR or HIPAA, the potential for unauthorized access and disruption of service could lead to violations of these regulations, which require protection of personal data and system availability.