CVE-2025-9363: Linksys Re6250 Buffer Overflow Vulnerability

CVE-2025-9363 Overview

CVE-2025-9363 is a stack-based buffer overflow in multiple Linksys range extender models, including the RE6250, RE6300, RE6350, RE6500, RE7000, and RE9000. The flaw resides in the portTriggerManageRule function exposed through the /goform/portTriggerManageRule endpoint. Attackers can exploit the issue by manipulating the triggerRuleName or schedule parameters, triggering memory corruption on the device. Remote exploitation is possible over the network, and the proof-of-concept has been publicly disclosed. Linksys was notified before publication but did not respond. The weakness is tracked under CWE-119 for improper restriction of operations within the bounds of a memory buffer.

Critical Impact
Remote attackers with low privileges can corrupt device memory through crafted port-trigger requests, potentially achieving code execution on affected Linksys range extenders.

Affected Products

Linksys RE6250 firmware 1.0.04.001 and RE6350 firmware 1.0.04.001
Linksys RE6300 firmware 1.2.07.001 and RE6500 firmware 1.0.013.001
Linksys RE7000 firmware 1.1.05.003 and RE9000 firmware 1.0.04.002

Discovery Timeline

2025-08-23 - CVE-2025-9363 published to the National Vulnerability Database
2025-09-02 - Last updated in NVD database

Technical Details for CVE-2025-9363

Vulnerability Analysis

The vulnerability is a classic stack-based buffer overflow reachable through the web management interface of affected Linksys range extenders. The portTriggerManageRule handler, exposed at /goform/portTriggerManageRule, processes user-controlled fields without validating their length before copying them into fixed-size stack buffers. Submitting overly long values for the triggerRuleName or schedule parameters overwrites adjacent stack memory, including the saved return address.

Because the affected models are consumer-grade embedded devices, mitigations such as Address Space Layout Randomization (ASLR), stack canaries, and non-executable stacks are often absent or inconsistently applied. This significantly increases the likelihood that memory corruption translates into reliable remote code execution under the privileges of the web service, typically root on these devices. Successful exploitation can lead to full device takeover, traffic interception, persistent backdoors on the local network, or pivoting to other internal hosts.

Root Cause

The root cause is missing input length validation in the portTriggerManageRule function. The handler copies attacker-supplied strings from HTTP POST parameters into stack buffers using unbounded string operations, allowing the input length to exceed the destination buffer size.

Attack Vector

Exploitation requires network access to the device's HTTP management interface and a low-privilege authenticated session. An attacker submits a crafted POST request to /goform/portTriggerManageRule containing an oversized triggerRuleName or schedule value. Detailed reproduction steps and a working PoC are published in the GitHub PoC for Vulnerability and indexed in VulDB #321066.

No verified exploitation code is reproduced here. Refer to the linked references for technical PoC details.

Detection Methods for CVE-2025-9363

Indicators of Compromise

Unexpected HTTP POST requests to /goform/portTriggerManageRule from internal or external sources, particularly with abnormally long triggerRuleName or schedule parameter values.
Unscheduled reboots, watchdog resets, or web service crashes on Linksys RE-series range extenders.
Outbound connections from the range extender to unknown hosts, indicating possible post-exploitation activity.

Detection Strategies

Inspect HTTP request bodies destined for /goform/ endpoints and alert on parameter values exceeding reasonable length thresholds, for example more than 256 bytes for rule names.
Deploy network IDS signatures that flag POST requests to portTriggerManageRule containing non-printable bytes or repeating padding patterns characteristic of buffer overflow payloads.
Baseline administrative traffic to range extenders and alert on access from non-management subnets.

Monitoring Recommendations

Forward router and extender syslog data to a centralized log platform and monitor for HTTP 5xx responses, segmentation faults, or process restarts tied to the web daemon.
Track DNS queries and outbound flows originating from range extender management IPs to detect command-and-control behavior post-compromise.

How to Mitigate CVE-2025-9363

Immediate Actions Required

Restrict access to the device web interface to trusted management VLANs and block WAN-side administration entirely.
Disable port triggering features if they are not required in the deployment.
Rotate administrative credentials on affected devices to limit reuse of captured low-privilege accounts.
Inventory affected RE6250, RE6300, RE6350, RE6500, RE7000, and RE9000 units and prioritize replacement planning, as Linksys did not respond to the disclosure.

Patch Information

At the time of publication, no vendor patch is available. The reporter states Linksys did not respond to the disclosure. Monitor the Linksys Official Website and the GitHub Vulnerability Documentation for firmware updates. Devices that are end-of-life should be replaced with currently supported hardware.

Workarounds

Place affected extenders behind a firewall rule that permits HTTP/HTTPS management traffic only from a dedicated administrator workstation.
Disable remote management and UPnP, and ensure the device is not reachable from the internet.
Segment IoT and consumer networking gear onto an isolated VLAN with no lateral access to sensitive systems.

bash

# Example iptables rule to restrict access to the range extender management interface
# Replace 192.0.2.10 with the trusted admin host and 192.0.2.50 with the extender IP
iptables -A FORWARD -s 192.0.2.10 -d 192.0.2.50 -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d 192.0.2.50 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.0.2.50 -p tcp --dport 443 -j DROP