CVE-2025-5854 Overview
CVE-2025-5854 is a buffer overflow vulnerability in the Tenda AC6 wireless router running firmware version 15.03.05.16. The flaw resides in the fromadvsetlanip function within /goform/AdvSetLanip, where the lanMask parameter is processed without proper bounds checking. Attackers with low-privileged network access can manipulate this argument to overflow an internal buffer and corrupt adjacent memory. The exploit details have been publicly disclosed, increasing the likelihood of opportunistic abuse against exposed devices. The vulnerability is tracked under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Critical Impact
A remote authenticated attacker can trigger memory corruption in Tenda AC6 firmware 15.03.05.16 via the lanMask parameter, potentially leading to arbitrary code execution or device compromise.
Affected Products
- Tenda AC6 router (hardware version 1.0)
- Tenda AC6 firmware version 15.03.05.16
- Web management interface endpoint /goform/AdvSetLanip
Discovery Timeline
- 2025-06-09 - CVE-2025-5854 published to NVD
- 2025-06-09 - Last updated in NVD database
Technical Details for CVE-2025-5854
Vulnerability Analysis
The vulnerability exists in the fromadvsetlanip handler exposed through the /goform/AdvSetLanip web endpoint of the Tenda AC6 router. This handler processes LAN configuration parameters submitted through the device's HTTP management interface. The lanMask argument is copied into a fixed-size stack or heap buffer without validating its length against the destination capacity. Supplying an oversized value overruns the buffer and corrupts adjacent memory structures, including saved return addresses on the stack. According to the EPSS estimate, the vulnerability has a probability score of 0.759%.
Root Cause
The root cause is the absence of length validation before invoking an unsafe string-copy routine inside fromadvsetlanip. The handler trusts attacker-controlled input from the HTTP request body and writes it directly into a bounded buffer. This pattern is common in embedded MIPS/ARM firmware where developers rely on functions such as strcpy or sprintf without enforcing maximum lengths.
Attack Vector
An attacker who can reach the router's web management interface and authenticate with low privileges submits a crafted POST request to /goform/AdvSetLanip. The request includes an excessively long value for the lanMask parameter. Processing this request triggers the overflow, which can corrupt control-flow data and crash the device. With careful payload construction, the corruption may be steered toward arbitrary code execution in the context of the embedded HTTP daemon. The vulnerability is exploitable over the network and requires no user interaction.
No verified exploit code is published in the referenced advisories. See the Notion Vulnerability Report and VulDB #311600 for technical analysis.
Detection Methods for CVE-2025-5854
Indicators of Compromise
- HTTP POST requests to /goform/AdvSetLanip containing abnormally long lanMask values
- Unexpected reboots, watchdog resets, or httpd crashes on Tenda AC6 devices
- Configuration changes to LAN subnet mask settings that do not match administrator activity
- Outbound connections from the router to unfamiliar IP addresses after suspicious management requests
Detection Strategies
- Inspect HTTP request bodies destined for the router's management interface and flag lanMask values exceeding expected octet-dotted notation length.
- Use network intrusion detection signatures that match POST /goform/AdvSetLanip requests with payload lengths beyond normal configuration sizes.
- Correlate management-interface authentication events with subsequent device reboots to identify exploitation attempts.
Monitoring Recommendations
- Forward router syslog and authentication logs to a centralized SIEM for behavioral analysis.
- Monitor administrative access to the router's web UI from non-management VLANs or external addresses.
- Track firmware version inventory to identify devices still running the vulnerable 15.03.05.16 build.
How to Mitigate CVE-2025-5854
Immediate Actions Required
- Restrict access to the Tenda AC6 web management interface so it is reachable only from trusted management networks.
- Disable remote (WAN-side) administration on all Tenda AC6 routers until a fix is available.
- Rotate router administrator credentials and enforce strong, unique passwords to limit access to authenticated endpoints.
- Audit the Tenda Official Website for firmware updates addressing this issue and apply them when released.
Patch Information
At the time of publication, no vendor patch is referenced in the NVD entry for CVE-2025-5854. Administrators should monitor the Tenda Official Website and the VulDB advisory for updates. If a fixed firmware image is released, schedule an upgrade window and validate device functionality after flashing.
Workarounds
- Place affected routers behind a segmentation firewall and block inbound HTTP/HTTPS to the management port from untrusted networks.
- Replace end-of-support Tenda AC6 hardware with a currently supported router platform where business requirements allow.
- Disable Universal Plug and Play (UPnP) and any other features that expose the management interface beyond the LAN.
- Use ACLs on upstream switches or firewalls to permit management traffic only from a dedicated administrative subnet.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
