CVE-2025-6112 Overview
CVE-2025-6112 is a buffer overflow vulnerability in the Tenda FH1205 router running firmware version 2.0.0.7. The flaw resides in the fromadvsetlanip function within the /goform/AdvSetLanip endpoint. Attackers can manipulate the lanMask argument to trigger a memory corruption condition. The vulnerability is remotely exploitable, and public disclosure of the exploit details increases the risk of weaponization. The issue is categorized under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer) and [CWE-120] (Classic Buffer Overflow).
Critical Impact
Remote attackers can corrupt memory on affected Tenda FH1205 devices by supplying a crafted lanMask parameter, potentially leading to denial of service or arbitrary code execution on the router.
Affected Products
- Tenda FH1205 hardware device
- Tenda FH1205 firmware version 2.0.0.7
- Deployments exposing the /goform/AdvSetLanip administrative endpoint
Discovery Timeline
- 2025-06-16 - CVE-2025-6112 published to NVD
- 2025-07-18 - Last updated in NVD database
Technical Details for CVE-2025-6112
Vulnerability Analysis
The vulnerability exists in the fromadvsetlanip function, which handles advanced LAN IP configuration requests sent to /goform/AdvSetLanip. The function processes the lanMask HTTP parameter without enforcing proper bounds checks before copying the value into a fixed-size stack or heap buffer. An authenticated attacker with low privileges on the management interface can submit a request containing an oversized lanMask value to corrupt adjacent memory regions.
Memory corruption in embedded router firmware frequently allows attackers to overwrite saved return addresses or function pointers. On MIPS or ARM-based SOHO devices like the FH1205, successful exploitation can lead to control-flow hijacking and arbitrary code execution within the context of the web management daemon, which typically runs as root.
The EPSS score of 0.621% reflects current exploitation probability estimates, but public disclosure of exploit details raises the likelihood of opportunistic scanning against exposed devices.
Root Cause
The root cause is the absence of length validation on the lanMask parameter before it is copied into an internal buffer inside fromadvsetlanip. The handler trusts client-supplied input from the HTTP request, violating safe string-handling practices typical of strcpy or sprintf usage in embedded C codebases.
Attack Vector
An attacker reaches the vulnerable code path by sending a crafted HTTP POST request to /goform/AdvSetLanip containing an oversized lanMask value. The attack requires network access to the device's management interface. While remote exploitation is feasible when the management plane is exposed to untrusted networks, devices that restrict administration to the LAN limit the attack surface to local adversaries. Technical proof-of-concept details have been published, as referenced in the Notion Document on Tenda FH1205 and VulDB #312581.
No verified exploit code is reproduced here. Refer to the linked advisories for technical specifics.
Detection Methods for CVE-2025-6112
Indicators of Compromise
- HTTP POST requests to /goform/AdvSetLanip containing abnormally long lanMask values exceeding standard subnet mask formats.
- Unexpected reboots, web service crashes, or watchdog resets on Tenda FH1205 devices.
- New outbound connections from the router to unfamiliar IP addresses following administrative requests.
- Configuration changes to LAN IP settings that were not initiated by an authorized administrator.
Detection Strategies
- Inspect HTTP traffic destined for the router management interface and alert on oversized parameters supplied to /goform/ endpoints.
- Deploy network-based intrusion detection signatures that match the fromadvsetlanip request pattern with non-IPv4-mask values in lanMask.
- Baseline normal administrative traffic volume and flag deviations targeting the FH1205 web UI.
Monitoring Recommendations
- Forward router syslog, authentication, and crash logs to a centralized SIEM for correlation across the network estate.
- Monitor for repeated authentication attempts followed by configuration requests, which may precede exploitation.
- Track firmware versions across deployed Tenda devices and alert when vulnerable versions appear on the network.
How to Mitigate CVE-2025-6112
Immediate Actions Required
- Restrict access to the router's web management interface to trusted administrative VLANs or hosts only.
- Disable remote (WAN-side) management on all Tenda FH1205 devices.
- Rotate administrator credentials and enforce strong, unique passwords on the management interface.
- Inventory all Tenda FH1205 deployments running firmware 2.0.0.7 and prioritize replacement or isolation.
Patch Information
At the time of publication, no vendor security advisory or patched firmware has been linked in the NVD record for CVE-2025-6112. Administrators should monitor the Tenda Official Website for firmware updates and consult VulDB CTI ID #312581 for tracking updates.
Workarounds
- Place affected devices behind a network firewall that blocks inbound access to TCP ports used by the web management interface.
- Segment SOHO routers from sensitive internal networks until a patched firmware version is available.
- Replace end-of-life or unmaintained Tenda FH1205 hardware with vendor-supported equipment that receives security updates.
- Disable unused services on the device to reduce the exposed attack surface.
# Configuration example: restrict management interface to a trusted host using upstream firewall (iptables)
iptables -A FORWARD -p tcp -d <FH1205_IP> --dport 80 -s <ADMIN_WORKSTATION_IP> -j ACCEPT
iptables -A FORWARD -p tcp -d <FH1205_IP> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <FH1205_IP> --dport 443 -s <ADMIN_WORKSTATION_IP> -j ACCEPT
iptables -A FORWARD -p tcp -d <FH1205_IP> --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
