CVE-2024-42815: TP-Link RE365 Buffer Overflow Vulnerability

CVE-2024-42815 Overview

CVE-2024-42815 is a stack-based buffer overflow [CWE-787] in the /usr/bin/httpd binary of the TP-Link RE365 V1_180213 Wi-Fi range extender. The flaw stems from missing length validation on the HTTP USER_AGENT header. A remote, unauthenticated attacker can send a crafted HTTP request to crash the device or execute arbitrary commands in the context of the web server. The web service exposed by the extender runs with elevated privileges on the embedded Linux firmware, making code execution equivalent to full device compromise.

Critical Impact
Unauthenticated attackers on the network can trigger remote code execution or denial of service on affected TP-Link RE365 devices by sending an oversized USER_AGENT header.

Affected Products

TP-Link RE365 hardware revision 1.0
TP-Link RE365 firmware build 180213 (V1_180213)
The embedded /usr/bin/httpd web server component

Discovery Timeline

2024-08-19 - CVE-2024-42815 published to NVD
2025-07-09 - Last updated in NVD database

Technical Details for CVE-2024-42815

Vulnerability Analysis

The vulnerability resides in the HTTP request parsing logic inside /usr/bin/httpd, the embedded web server running on the TP-Link RE365 range extender. When the server processes incoming HTTP requests, it reads the User-Agent header value into a fixed-size stack buffer without enforcing an upper bound on the input length. An attacker can supply a User-Agent value that exceeds the destination buffer, overwriting adjacent stack memory including the saved return address.

Because the device exposes its web management interface over the local network, exploitation requires no authentication and no user interaction. A successful overflow yields one of two outcomes: a crash of the httpd process that disrupts management and may destabilize the device, or arbitrary command execution achieved by redirecting control flow into attacker-supplied shellcode or by chaining return-oriented programming gadgets present in the firmware.

Root Cause

The root cause is missing bounds checking on the USER_AGENT field during HTTP header parsing. The code uses an unsafe copy operation that trusts the length of the attacker-controlled header, a classic out-of-bounds write pattern tracked as [CWE-787]. Consumer-grade router firmware frequently ships without modern memory protections such as stack canaries or full address space layout randomization, which makes the overflow directly exploitable.

Attack Vector

The attack vector is network-adjacent over HTTP. An attacker on the same Wi-Fi network, or any network with reachability to the device's management interface, sends an HTTP request containing an oversized User-Agent header to the listening port of /usr/bin/httpd. No credentials, configuration changes, or victim interaction are required. The vulnerability mechanism and a proof-of-concept request are described in the public references; see the GitHub PoC Repository and the Security Online CVE Analysis for technical details.

Detection Methods for CVE-2024-42815

Indicators of Compromise

HTTP requests to the RE365 management interface containing abnormally long User-Agent header values, typically several hundred bytes or more.
Unexpected reboots or crashes of the httpd process on the extender, often visible as loss of management interface availability.
Outbound connections from the extender to unfamiliar hosts, which can indicate post-exploitation command-and-control activity.
Unauthorized configuration changes such as modified DNS settings, new administrative sessions, or altered Wi-Fi credentials.

Detection Strategies

Inspect HTTP traffic destined for management interfaces of consumer network equipment and flag User-Agent values that exceed a reasonable length threshold (for example, 512 bytes).
Apply intrusion detection signatures that match oversized or non-printable byte sequences inside HTTP request headers sent to embedded device IP ranges.
Correlate management interface crashes with preceding HTTP traffic to identify exploitation attempts even when the overflow does not result in code execution.

Monitoring Recommendations

Restrict and log access to the RE365 web management interface and alert on any access from non-administrative subnets.
Monitor egress traffic from extenders and IoT segments for new destinations, unusual ports, or TLS connections to low-reputation infrastructure.
Maintain an inventory of TP-Link RE365 devices and firmware versions, and alert when devices running firmware build 180213 appear on the network.

How to Mitigate CVE-2024-42815

Immediate Actions Required

Remove the RE365 management interface from any network reachable by untrusted users and disable remote management features.
Place the extender on a segmented Wi-Fi or VLAN that blocks lateral access to corporate or sensitive resources.
Apply firewall rules on upstream gateways to permit HTTP access to the device only from a dedicated administrative host.
Replace the device with a currently supported model if no firmware update is available from TP-Link.

Patch Information

At the time of NVD publication, no vendor advisory or fixed firmware version was listed in the references for CVE-2024-42815. Administrators should consult the TP-Link support site for the RE365 product line and apply the latest available firmware. If the vendor has not released a fix for firmware build 180213, the device should be considered end-of-life from a security perspective and replaced.

Workarounds

Disable the HTTP management service when not actively in use, where the device firmware permits this.
Bind administrative access to a wired interface and disable management over Wi-Fi.
Use an upstream proxy or web application firewall to drop HTTP requests with User-Agent headers longer than a strict allowlisted size before they reach the extender.

bash

# Example upstream iptables rule to limit access to the RE365 web UI
# Replace 192.0.2.10 with the extender IP and 198.51.100.5 with the admin host
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -s 198.51.100.5 -j ACCEPT
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -j DROP