CVE-2026-82770: Contec RP-WAH-SR Buffer Overflow Flaw

CVE-2026-82770 Overview

CVE-2026-82770 is a buffer overflow vulnerability in the Contec RP-WAH-SR Series wireless access point product line. The flaw resides in the device's web service. A remote attacker who sends a specially crafted request can trigger the overflow and execute an arbitrary program on the affected device. The issue is classified under CWE-120 (Classic Buffer Overflow) and requires low-privilege authentication to exploit over the network.

Critical Impact
Successful exploitation allows a remote authenticated attacker to execute arbitrary programs on the RP-WAH-SR device, resulting in full compromise of confidentiality, integrity, and availability of the wireless access point.

Affected Products

Contec RP-WAH-SR Series wireless access points
Refer to the Contec Security Information PDF for specific firmware versions
See the JVN Vulnerability Report for the full advisory

Discovery Timeline

2026-09-14 - CVE-2026-82770 published to NVD
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-82770

Vulnerability Analysis

The vulnerability is a classic buffer overflow in the web service running on Contec RP-WAH-SR Series devices. An authenticated remote attacker sends a crafted HTTP request that contains data exceeding the size of a fixed-length buffer used by the web service. When the service copies attacker-controlled input into the undersized buffer, adjacent memory is overwritten. This condition can be leveraged to redirect execution flow and run an arbitrary program on the device.

Exploitation is performed over the network with low attack complexity. The attacker must hold a low-privilege account on the target, but no user interaction is required. Because the affected component is embedded firmware on a wireless access point, successful exploitation gives an attacker a foothold at the network edge and a pivot into internal network segments.

Root Cause

The root cause is insufficient bounds checking on input processed by the device's web service. Input length is not validated before it is written into a fixed-size buffer, allowing memory corruption when oversized payloads are supplied. This pattern is characteristic of CWE-120, where the receiving buffer is smaller than the source data and no length restriction is enforced.

Attack Vector

The attack vector is network-based against the device's HTTP management interface. An attacker who can reach the web service and authenticate with a low-privilege account crafts an HTTP request containing an oversized field to overflow the vulnerable buffer. Devices exposed to untrusted networks, or reachable from a compromised internal host, are the primary exposure. No exploit code or public proof-of-concept is currently listed for this issue.

See the JVN Vulnerability Report and Contec Security Information PDF for vendor-supplied technical details.

Detection Methods for CVE-2026-82770

Indicators of Compromise

Unexpected HTTP POST or GET requests to the RP-WAH-SR web management interface containing abnormally long parameter values or headers.
Web service crashes, unexpected restarts, or watchdog reboots on RP-WAH-SR devices.
Outbound connections from the access point to unfamiliar IP addresses following administrative HTTP traffic.
New or unfamiliar processes running on the device that were not part of the factory firmware.

Detection Strategies

Deploy network intrusion detection signatures that flag oversized HTTP request fields directed at Contec RP-WAH-SR management endpoints.
Baseline normal administrative traffic patterns to the device and alert on deviations in request size, source IP, or authentication frequency.
Correlate authentication events on the access point with subsequent malformed or oversized HTTP requests.

Monitoring Recommendations

Forward device syslog and web service logs to a centralized log platform for retention and analysis.
Monitor for repeated failed authentication attempts followed by successful low-privilege logins to the web interface.
Alert on any change to firmware version, running configuration, or administrative account list on the device.

How to Mitigate CVE-2026-82770

Immediate Actions Required

Restrict access to the RP-WAH-SR web management interface to trusted administrative networks only.
Rotate all administrative and low-privilege credentials on affected devices to reduce the risk of authenticated exploitation.
Inventory all RP-WAH-SR Series devices in the environment and confirm firmware versions against the vendor advisory.
Apply the vendor-supplied firmware update as soon as it is available for the deployed model.

Patch Information

Contec has published a security advisory for the RP-WAH-SR Series. Review the Contec Security Information PDF for affected firmware versions and update instructions. The JVN Vulnerability Report mirrors the coordinated disclosure details.

Workarounds

Place affected access points on a segmented management VLAN unreachable from user or guest networks.
Enforce firewall access control lists that allow HTTP management traffic only from designated administrator workstations.
Disable remote management over untrusted interfaces where operationally feasible.
Require multi-factor or jump-host access for administrators authenticating to the device web interface.

bash

# Example: restrict web management to a trusted admin subnet using an upstream firewall
iptables -A FORWARD -p tcp -s 10.10.50.0/24 -d <RP-WAH-SR-IP> --dport 80 -j ACCEPT
iptables -A FORWARD -p tcp -d <RP-WAH-SR-IP> --dport 80 -j DROP
iptables -A FORWARD -p tcp -s 10.10.50.0/24 -d <RP-WAH-SR-IP> --dport 443 -j ACCEPT
iptables -A FORWARD -p tcp -d <RP-WAH-SR-IP> --dport 443 -j DROP