CVE-2023-41229 in DIR-3040
Summary
by MITRE • 05/03/2024
D-Link DIR-3040 HTTP Request Processing Referer Heap-Based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of D-Link DIR-3040 routers. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the prog.cgi binary, which handles HNAP requests made to the lighttpd webserver listening on TCP ports 80 and 443. The issue results from the lack of proper validation of a user-supplied string before copying it to a heap-based buffer. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-21671.
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Analysis
by VulDB Data Team • 06/23/2026
This vulnerability represents a critical heap-based buffer overflow in the D-Link DIR-3040 router firmware that stems from improper input validation within the prog.cgi binary component. The flaw specifically manifests when processing HTTP requests containing maliciously crafted Referer headers, allowing attackers to overwrite adjacent heap memory locations through a classic buffer overflow exploit. The vulnerability resides in the lighttpd webserver implementation that listens on standard TCP ports 80 and 443, making it accessible to network-adjacent attackers without requiring authentication credentials. This represents a severe security weakness classified under CWE-121 as heap-based buffer overflow, where insufficient bounds checking permits arbitrary memory corruption that can be exploited for privilege escalation.
The technical exploitation of this vulnerability occurs through the manipulation of HTTP request headers during HNAP (Home Network Access Protocol) processing, which is a common protocol used by home routers for configuration management. When the prog.cgi binary receives an HTTP request with an oversized Referer header, it fails to validate the input length before copying the string data into a heap-allocated buffer. This lack of proper input sanitization creates a predictable memory corruption scenario where attacker-controlled data can overwrite critical heap metadata or adjacent memory structures. The vulnerability's remote code execution capability arises because the affected binary runs with root privileges, meaning successful exploitation grants full system compromise and administrative control over the router.
The operational impact of this vulnerability extends beyond simple unauthorized access as it provides attackers with complete control over the affected network infrastructure. Network-adjacent attackers can leverage this issue to establish persistent backdoors, redirect traffic through malicious proxies, or use the compromised device as a launching point for broader network attacks. This vulnerability particularly affects enterprise and home networks where D-Link DIR-3040 routers are deployed, creating potential risks for data exfiltration, man-in-the-middle attacks, and denial-of-service conditions. The absence of authentication requirements significantly amplifies the threat surface, as attackers can exploit this without requiring prior access credentials or network reconnaissance.
Security mitigation strategies should prioritize immediate firmware updates from D-Link to address the buffer overflow condition in prog.cgi, while network administrators should implement firewall rules to restrict access to TCP ports 80 and 443 from untrusted networks. Additional defensive measures include monitoring for suspicious Referer header patterns in web server logs, implementing network segmentation to limit lateral movement, and conducting vulnerability assessments to identify other potentially affected devices within the network infrastructure. The ATT&CK framework categorizes this vulnerability under T1210 exploitation techniques involving remote code execution through web application flaws, while the CWE classification of heap-based buffer overflow emphasizes the importance of proper memory management practices during input handling operations. Organizations should also consider deploying intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability pattern.