D-Link DIR-825 Buffer Overflow Vulnerability in miniupnpd

A buffer overflow vulnerability, identified as CVE-2026-7069, has been discovered in D-Link DIR-825 routers with firmware versions up to 3.00b32. The vulnerability resides within the AddPortMapping function of the upnpsoap.c file, part of the miniupnpd component. An attacker on the local network can exploit this vulnerability by manipulating the NewPortMappingDescription argument, leading to a buffer overflow. Given that the exploit is publicly available, the risk of exploitation is elevated. This vulnerability is especially critical as it affects end-of-life products, meaning that official patches are unlikely to be released.

Attack Chain

1. Attacker gains access to the local network, either through physical access or compromising a device on the network.
2. The attacker identifies a vulnerable D-Link DIR-825 router running a firmware version up to 3.00b32.
3. The attacker crafts a malicious SOAP request targeting the UPnP service on the router.
4. The crafted request includes a NewPortMappingDescription argument with a payload exceeding the buffer’s capacity in the AddPortMapping function within upnpsoap.c.
5. The router’s miniupnpd component processes the SOAP request, triggering the buffer overflow when writing the overly long NewPortMappingDescription.
6. The buffer overflow overwrites adjacent memory locations, potentially including critical function pointers or return addresses.
7. The attacker redirects execution flow to malicious code injected into the overflowed buffer.
8. The attacker executes arbitrary code on the router, potentially gaining full control of the device or using it as a pivot point to attack other devices on the network.

Impact

Successful exploitation of CVE-2026-7069 allows an attacker on the local network to execute arbitrary code on the vulnerable D-Link DIR-825 router. This can lead to complete compromise of the router, allowing the attacker to eavesdrop on network traffic, modify DNS settings, or use the router to launch attacks against other devices within the network or on the internet. Given the end-of-life status of the affected devices, a large number of potentially vulnerable routers may remain in use, making this a significant threat.

Recommendation

• Disable UPnP on D-Link DIR-825 routers where possible to prevent exploitation of CVE-2026-7069.
• Monitor network traffic for suspicious SOAP requests targeting the UPnP service (miniupnpd) on internal network devices using a network intrusion detection system (NIDS). Deploy the Sigma rule targeting HTTP POST requests to the UPnP service.
• Segment networks to limit the impact of a compromised router in case of successful exploitation.