CVE-2026-13564 Overview
CVE-2026-13564 is a stack-based buffer overflow vulnerability in the Edimax EW-7478APC wireless access point running firmware version 1.04. The flaw resides in the formPPPoESetup function within /goform/formPPPoESetup, which is part of the device's POST request handler. Manipulating the pppUserName argument triggers the overflow. Attackers can exploit the vulnerability remotely over the network, and a public exploit is available. The vendor was contacted about the disclosure but did not respond. The weakness is tracked under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Critical Impact
Remote authenticated attackers can corrupt stack memory on the device, potentially achieving arbitrary code execution or denial of service against the access point.
Affected Products
- Edimax EW-7478APC wireless access point
- Firmware version 1.04
- The formPPPoESetup handler in /goform/formPPPoESetup
Discovery Timeline
- 2026-06-29 - CVE-2026-13564 published to NVD
- 2026-06-29 - Last updated in NVD database
Technical Details for CVE-2026-13564
Vulnerability Analysis
The vulnerability is a stack-based buffer overflow in the formPPPoESetup function used to configure PPP over Ethernet (PPPoE) credentials on the Edimax EW-7478APC. When the device processes a POST request to /goform/formPPPoESetup, the handler copies the attacker-controlled pppUserName parameter into a fixed-size stack buffer without validating its length. Supplying an oversized value overwrites adjacent stack data, including saved return addresses and function pointers.
Exploitation requires network access to the device's management interface and low-level privileges. Successful exploitation compromises confidentiality, integrity, and availability of the device. Public exploit details are hosted on external write-ups, and the EPSS score of 0.751% reflects a modest but non-trivial likelihood of near-term exploitation.
Root Cause
The root cause is missing bounds checking on the pppUserName POST parameter before it is copied into a stack-allocated buffer. The handler assumes user-supplied input conforms to expected length constraints, a common defect in embedded web management interfaces written in C without safe string routines.
Attack Vector
The attack vector is network-based. An attacker who can reach the device's HTTP management interface submits a crafted POST request to /goform/formPPPoESetup with an overlong pppUserName field. Because the exploit has been made public and the vendor has not issued a fix, unpatched devices exposed to untrusted networks remain at risk.
No verified proof-of-concept code is republished here. See the Notion write-up for EDIMAX EW-7478APC formPPPoESetup and VulDB entry for CVE-2026-13564 for technical specifics.
Detection Methods for CVE-2026-13564
Indicators of Compromise
- Unexpected HTTP POST requests to /goform/formPPPoESetup originating from external or unusual internal hosts.
- Anomalously long pppUserName values in captured management-interface traffic.
- Access point reboots, crash logs, or PPPoE service restarts following administrative HTTP activity.
Detection Strategies
- Deploy network intrusion detection signatures that flag POST requests to formPPPoESetup containing pppUserName fields exceeding expected length (for example, more than 64 bytes).
- Perform deep packet inspection on traffic destined for embedded device management ports and alert on non-printable or shellcode-like byte patterns.
- Correlate device availability drops with preceding HTTP administrative activity in log aggregation platforms.
Monitoring Recommendations
- Forward Edimax device syslog output to a central log platform and alert on formPPPoESetup errors or watchdog resets.
- Monitor administrative interfaces for unauthorized source addresses and repeated authentication attempts.
- Track outbound connections from the access point that could indicate post-exploitation command-and-control activity.
How to Mitigate CVE-2026-13564
Immediate Actions Required
- Remove Edimax EW-7478APC devices running firmware 1.04 from any network segment reachable by untrusted users.
- Restrict access to the HTTP management interface to a dedicated administrative VLAN or jump host.
- Rotate PPPoE and administrative credentials that may have been exposed on affected devices.
- Inventory Edimax EW-7478APC deployments and schedule replacement or isolation for units without vendor support.
Patch Information
No vendor patch is available. According to the disclosure, Edimax was notified early but did not respond. Organizations should treat firmware 1.04 as unsupported and plan for device replacement or compensating controls until a fix is published.
Workarounds
- Block external access to the device's web management port at the perimeter firewall.
- Disable the PPPoE configuration workflow if the deployment does not require it.
- Place vulnerable devices behind a reverse proxy or WAF that enforces strict length limits on pppUserName and other POST parameters.
- Replace end-of-life Edimax EW-7478APC hardware with a supported access point.
# Example ACL restricting management interface access to an admin subnet
iptables -A INPUT -p tcp --dport 80 -s 10.10.50.0/24 -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.
