CVE-2026-13583 Overview
CVE-2026-13583 is a buffer overflow vulnerability in the Edimax EW-7478APC wireless access point running firmware version 1.04. The flaw resides in the formUSBFolder function handling POST requests to /goform/formUSBFolder. Attackers can trigger memory corruption by manipulating the ShareName or SelectName arguments. The vulnerability is remotely exploitable and requires low-privilege authentication. Public disclosure includes exploit details, increasing the likelihood of opportunistic attacks. According to VulDB, the vendor was contacted prior to disclosure but did not respond. This weakness is classified under [CWE-119], improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers with low privileges can trigger a buffer overflow in the EW-7478APC web management interface, potentially leading to arbitrary code execution or denial of service on affected access points.
Affected Products
- Edimax EW-7478APC firmware version 1.04
- formUSBFolder function in /goform/formUSBFolder
- POST Request Handler component processing ShareName and SelectName parameters
Discovery Timeline
- 2026-06-29 - CVE-2026-13583 published to NVD
- 2026-07-01 - Last updated in NVD database
- 2026-07-02 - EPSS score assessment recorded at 0.445%
Technical Details for CVE-2026-13583
Vulnerability Analysis
The vulnerability is a classic stack or heap buffer overflow in an embedded web management endpoint. The formUSBFolder handler processes POST requests intended to configure USB share folder settings on the access point. Two parameters, ShareName and SelectName, are copied into fixed-size buffers without sufficient length validation. An attacker submitting oversized input can overwrite adjacent memory regions. On MIPS or ARM-based embedded devices such as the EW-7478APC, this class of flaw commonly enables control of return addresses or function pointers. Successful exploitation yields code execution in the context of the web server process, which typically runs with elevated privileges on consumer network hardware.
Root Cause
The root cause is missing bounds checking in the formUSBFolder function when copying user-controlled strings into internal buffers. The handler trusts input length from the HTTP POST body and uses unsafe string operations such as strcpy or sprintf without size limits. This aligns with [CWE-119], a common defect in older embedded firmware written in C.
Attack Vector
The attack originates over the network against the device's HTTP management interface. The attacker must possess low-level credentials to reach the /goform/formUSBFolder endpoint. Once authenticated, the attacker crafts a POST request with an oversized ShareName or SelectName value. No user interaction is required. The exploit has been publicly disclosed through VulDB entry #374589 and detailed in the technical write-up on Notion.
No verified proof-of-concept code is reproduced here. Refer to the linked references for technical exploitation details.
Detection Methods for CVE-2026-13583
Indicators of Compromise
- HTTP POST requests to /goform/formUSBFolder containing abnormally long ShareName or SelectName values.
- Unexpected reboots, crashes, or web interface unavailability on Edimax EW-7478APC devices.
- Outbound connections from the access point to unfamiliar IP addresses following administrative requests.
Detection Strategies
- Deploy network intrusion detection signatures that flag POST bodies exceeding expected length for ShareName and SelectName fields.
- Monitor management interface access logs for repeated authentication attempts followed by requests to /goform/formUSBFolder.
- Baseline the device's normal HTTP request patterns and alert on payload size anomalies.
Monitoring Recommendations
- Aggregate device syslog and management traffic into a centralized SIEM for behavioral analysis.
- Track firmware version inventory to identify unpatched EW-7478APC units on the network.
- Alert on any lateral movement or scanning activity originating from wireless access point management VLANs.
How to Mitigate CVE-2026-13583
Immediate Actions Required
- Restrict access to the EW-7478APC web management interface to trusted administrative networks only.
- Change default and low-privilege credentials to strong, unique values to raise the bar for authenticated exploitation.
- Disable USB share configuration functionality if it is not required in the deployment.
- Segment affected devices onto a dedicated VLAN with strict egress filtering.
Patch Information
At the time of publication, no vendor patch is available. VulDB reports that Edimax was contacted about the disclosure but did not respond. Monitor the Edimax support portal and the VulDB advisory for firmware updates.
Workarounds
- Place the access point behind a firewall that blocks external access to TCP ports used by the management HTTP service.
- Require VPN authentication before administrators can reach the device management interface.
- Consider replacing end-of-support Edimax hardware with actively maintained models if no patch is released.
# Example firewall rule limiting management access to a trusted subnet
iptables -A INPUT -p tcp --dport 80 -s 10.10.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
