CVE-2025-7911 in DI-8100
Summary
by MITRE • 07/21/2025
A vulnerability classified as critical was found in D-Link DI-8100 1.0. This vulnerability affects the function sprintf of the file /upnp_ctrl.asp of the component jhttpd. The manipulation of the argument remove_ext_proto/remove_ext_port leads to stack-based buffer overflow. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 08/08/2025
This critical vulnerability exists within the D-Link DI-8100 1.0 router firmware, specifically within the jhttpd web server component that handles Universal Plug and Play UPnP functionality. The flaw resides in the sprintf function call within the /upnp_ctrl.asp file, which processes user-supplied input parameters. The vulnerability manifests when the remove_ext_proto and remove_ext_port arguments are manipulated, creating conditions that allow attackers to overflow stack buffers through improper input validation and handling. The stack-based buffer overflow occurs because the application fails to properly validate the length of input data before copying it into fixed-size buffers, creating opportunities for arbitrary code execution and system compromise.
The technical implementation of this vulnerability follows a classic stack buffer overflow pattern where insufficient bounds checking allows attackers to overwrite adjacent memory locations on the program stack. This type of vulnerability is classified under CWE-121 Stack-based Buffer Overflow, which represents a fundamental flaw in memory management where data written to a buffer exceeds the allocated memory boundaries. The attack vector is remote and accessible through the web interface of the router, making exploitation straightforward for attackers who can send malicious HTTP requests to the affected device. The fact that a public exploit has been disclosed significantly increases the threat level, as it removes the requirement for advanced exploitation techniques and makes the vulnerability immediately actionable by threat actors.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and potential network infiltration. An attacker who successfully exploits this vulnerability can execute arbitrary code with the privileges of the jhttpd process, which typically runs with elevated privileges to manage network services and device configuration. This could lead to persistent backdoor access, network traffic interception, modification of router configuration settings, or use of the device as a pivot point for attacking other systems within the local network. The vulnerability affects the core UPnP functionality that allows external devices to communicate with the router, making it particularly dangerous as it can be exploited without requiring physical access to the device or knowledge of the network configuration.
Mitigation strategies should focus on immediate firmware updates from D-Link, as this is the most effective defense against the known exploit. Network administrators should also implement firewall rules to restrict access to the router's web interface from untrusted networks and consider disabling UPnP functionality if it is not required for network operations. The implementation of network segmentation and monitoring can help detect anomalous traffic patterns that may indicate exploitation attempts. Additionally, organizations should conduct comprehensive vulnerability assessments of their network infrastructure to identify other potentially affected devices, as similar vulnerabilities may exist in other network equipment from the same vendor or using similar software components. This vulnerability demonstrates the importance of proper input validation and secure coding practices, particularly in network services that handle external input, aligning with ATT&CK technique T1059.007 for command and scripting interpreter and T1566.001 for credential access through exploitation of network protocols.