CVE-2024-2558 Overview
CVE-2024-2558 is a stack-based buffer overflow vulnerability in the Tenda AC18 wireless router running firmware version 15.03.05.05. The flaw resides in the formexeCommand function handling requests to the /goform/execCommand endpoint. Attackers manipulate the cmdinput argument to overflow a stack buffer, enabling remote exploitation over the network. The vulnerability is tracked as VulDB entry VDB-257057. According to the disclosure record, Tenda was contacted early but did not respond to the researcher. Public exploit details were released alongside the disclosure.
Critical Impact
Remote authenticated attackers can trigger a stack-based buffer overflow in Tenda AC18 routers, potentially executing arbitrary code with router-level privileges and gaining full control of the device.
Affected Products
- Tenda AC18 router (hardware)
- Tenda AC18 firmware version 15.03.05.05
- Deployments exposing the /goform/execCommand web management endpoint
Discovery Timeline
- 2024-03-17 - CVE-2024-2558 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-2558
Vulnerability Analysis
The vulnerability is a stack-based buffer overflow [CWE-121] and out-of-bounds write [CWE-787] in the formexeCommand handler. This handler processes HTTP requests submitted to /goform/execCommand, a web management interface endpoint on the Tenda AC18 router. The cmdinput parameter supplied by the client is copied into a fixed-size stack buffer without proper length validation. Writing beyond the buffer boundary corrupts adjacent stack memory, including saved return addresses and frame pointers.
Successful exploitation allows an attacker to redirect execution flow. On embedded MIPS or ARM devices such as the AC18, missing exploit mitigations like stack canaries, ASLR, and non-executable stacks make reliable arbitrary code execution feasible. An attacker who reaches this handler can compromise confidentiality, integrity, and availability of the router.
Root Cause
The root cause is insufficient bounds checking when copying attacker-controlled input from the cmdinput HTTP parameter into a fixed-size stack buffer inside formexeCommand. The function trusts the length of the supplied argument rather than enforcing a maximum size. This coding pattern is common in Tenda firmware and other consumer-grade embedded web servers built on stripped-down HTTP daemons.
Attack Vector
Exploitation occurs over the network against the router's HTTP management interface. The attacker sends a crafted POST or GET request to /goform/execCommand containing an oversized cmdinput value. The request requires low privileges, meaning an attacker with access to the management interface, whether from the LAN or an exposed WAN interface, can trigger the flaw. No user interaction is required. A public proof-of-concept describing the request format is documented in the GitHub PoC Repository.
Detection Methods for CVE-2024-2558
Indicators of Compromise
- HTTP requests to /goform/execCommand containing abnormally long cmdinput parameter values
- Unexpected reboots or crashes of the Tenda AC18 web management daemon (httpd)
- Outbound connections from the router to unknown hosts, indicating post-exploitation callbacks
- New or modified iptables rules, DNS settings, or firmware images on the device
Detection Strategies
- Inspect network traffic to router management interfaces for POST requests to /goform/execCommand with cmdinput values exceeding expected lengths.
- Deploy network intrusion detection signatures that flag requests to Tenda goform endpoints originating from untrusted network segments.
- Correlate router log anomalies, such as service restarts, with inbound HTTP requests to the management interface.
Monitoring Recommendations
- Monitor router administrative interfaces for exposure to WAN or untrusted VLANs.
- Track authentication events on the router web interface and alert on repeated failures followed by successful logins.
- Baseline outbound connections from network infrastructure devices and alert on deviations.
How to Mitigate CVE-2024-2558
Immediate Actions Required
- Restrict access to the Tenda AC18 web management interface to trusted management VLANs only, and disable remote WAN administration.
- Change default and weak administrator credentials to reduce the risk from the low-privilege prerequisite in the attack chain.
- Isolate affected AC18 devices from segments hosting sensitive assets until a vendor fix is available.
- Review router configuration and firmware integrity for signs of tampering.
Patch Information
At the time of publication, no vendor patch is available. VulDB records indicate the vendor was contacted early but did not respond. Organizations should track Tenda's product firmware pages for updates and consult the VulDB advisory for status changes. Consider replacing affected AC18 devices with hardware from vendors that provide timely security updates if no fix is issued.
Workarounds
- Block external access to TCP ports serving the router management HTTP interface at an upstream firewall.
- Place vulnerable AC18 devices behind a network segmentation boundary that permits management traffic only from a dedicated jump host.
- Disable the web management service when not actively administering the device, where the firmware permits it.
# Example upstream firewall rule to restrict router admin access to a management subnet
iptables -A FORWARD -p tcp -d 192.0.2.1 --dport 80 -s 10.10.10.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d 192.0.2.1 --dport 80 -j DROP
iptables -A FORWARD -p tcp -d 192.0.2.1 --dport 443 -s 10.10.10.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d 192.0.2.1 --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
