CVE-2025-5608 Overview
CVE-2025-5608 is a buffer overflow vulnerability in the Tenda AC18 wireless router running firmware version 15.03.05.05. The flaw resides in the formsetreboottimer function within the /goform/SetSysAutoRebbotCfg endpoint. Attackers can manipulate the rebootTime argument to trigger memory corruption over the network. Public disclosure of the exploit technique has occurred through third-party vulnerability databases. The weakness maps to [CWE-119] and [CWE-120], covering improper restriction of operations within memory buffers and classic buffer copy without size checking.
Critical Impact
Authenticated remote attackers can overflow a stack buffer in the router's HTTP management interface, potentially leading to arbitrary code execution or denial of service on the device.
Affected Products
- Tenda AC18 hardware router
- Tenda AC18 firmware version 15.03.05.05
- Any deployment exposing the /goform/SetSysAutoRebbotCfg management endpoint
Discovery Timeline
- 2025-06-04 - CVE-2025-5608 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-5608
Vulnerability Analysis
The vulnerability exists in the formsetreboottimer handler that processes automatic reboot scheduling requests. When a client submits a POST request to /goform/SetSysAutoRebbotCfg, the handler reads the rebootTime parameter directly from user input. The function copies this attacker-controlled value into a fixed-size stack buffer without validating the input length. Overwriting adjacent memory allows an attacker to corrupt the saved return address and hijack execution flow within the router's HTTP daemon process.
Because the AC18 firmware runs the web management daemon with elevated privileges and lacks modern exploit mitigations such as consistent stack canaries and full address space layout randomization, exploitation is practical against embedded MIPS or ARM builds. Successful exploitation compromises confidentiality, integrity, and availability of the device according to the CVSS vector.
Root Cause
The root cause is missing bounds checking on the rebootTime HTTP parameter before it is passed to an unsafe string-handling operation. The developer trusts input length rather than validating it against the destination buffer size, matching the pattern described by [CWE-120].
Attack Vector
Exploitation requires network reachability to the router's web management interface and low-privilege authentication. An attacker on the LAN, or on the WAN if remote management is enabled, can send a crafted HTTP POST body containing an oversized rebootTime value to /goform/SetSysAutoRebbotCfg. No user interaction is required.
Detailed reproduction steps have been documented in the Notion Security Report and cataloged in VulDB #311094.
Detection Methods for CVE-2025-5608
Indicators of Compromise
- HTTP POST requests to /goform/SetSysAutoRebbotCfg containing rebootTime values exceeding typical scheduling strings (more than 32 bytes).
- Unexpected reboots, service crashes, or httpd process restarts on Tenda AC18 devices.
- New administrative sessions or configuration changes originating from unfamiliar internal or external IP addresses.
Detection Strategies
- Inspect HTTP traffic destined for router management interfaces for oversized parameters in goform endpoints.
- Deploy network IDS signatures that flag POST requests to SetSysAutoRebbotCfg with abnormal payload sizes or shellcode-like byte patterns.
- Correlate router syslog reboots with preceding management-plane HTTP traffic to identify exploitation attempts.
Monitoring Recommendations
- Forward router syslog and administrative access logs to a centralized SIEM for retention and alerting.
- Monitor for authentication events on the router management interface from non-administrator subnets.
- Track firmware version inventory across Tenda AC18 devices to identify unpatched units.
How to Mitigate CVE-2025-5608
Immediate Actions Required
- Disable remote WAN management on all Tenda AC18 routers until a vendor patch is installed.
- Restrict LAN access to the router web interface to a dedicated management VLAN or trusted administrative hosts.
- Rotate router administrator credentials and enforce strong, unique passwords to reduce the value of low-privilege access.
- Segment IoT and consumer network gear away from sensitive production or corporate resources.
Patch Information
At the time of publication, no vendor advisory or fixed firmware release has been listed in the NVD references. Consult the Tenda Official Website for firmware updates addressing the formsetreboottimer handler. Until a patched build is available, treat all AC18 devices running firmware 15.03.05.05 as exposed.
Workarounds
- Block inbound TCP connections to the router HTTP or HTTPS management ports at the network edge.
- Place vulnerable devices behind an upstream firewall that filters requests to /goform/SetSysAutoRebbotCfg.
- Replace end-of-support Tenda AC18 units with a supported router platform if a firmware fix does not become available.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
