CVE-2026-108906 Overview
CVE-2026-108906 is an out-of-bounds read vulnerability affecting Netcore NR268 firmware version 1.7.121109. The flaw resides in the filter_arp_put_file_cgi function within /router/filter_arp_put_file.cgi. Manipulation of the put_file argument triggers the out-of-bounds read condition. Attackers can initiate the attack remotely over the network. The exploit has been publicly disclosed, increasing the risk of opportunistic use against exposed devices. The vendor was contacted prior to public disclosure but did not respond. The weakness maps to [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Critical Impact
Remote attackers with high privileges can trigger memory disclosure in the router's HTTP management interface, potentially exposing sensitive runtime data from the device.
Affected Products
- Netcore NR268 router, firmware version 1.7.121109
- The /router/filter_arp_put_file.cgi endpoint on affected firmware
- The filter_arp_put_file_cgi function processing the put_file argument
Discovery Timeline
- 2026-10-12 - CVE-2026-108906 published to the National Vulnerability Database (NVD)
- 2026-10-15 - Last updated in NVD database
Technical Details for CVE-2026-108906
Vulnerability Analysis
The vulnerability occurs in the filter_arp_put_file_cgi handler, which processes ARP table import requests submitted to /router/filter_arp_put_file.cgi. When the function parses the put_file argument, it reads memory outside the intended buffer bounds. This behavior is classified under [CWE-119] and specifically presents as an out-of-bounds read. An authenticated remote attacker can repeatedly send crafted requests to leak adjacent memory contents, which may contain configuration data, credentials, or session material. Because the issue is reachable through the router's web interface, exploitation does not require physical proximity. The vendor has not acknowledged the disclosure, so no official fix is available at the time of publication.
Root Cause
The root cause is improper validation of the length or structure of data referenced by the put_file parameter during ARP import processing. The CGI handler reads beyond the allocated buffer when the input does not match the expected format or size. Public technical analysis is available in the GitHub Report on ARP Import.
Attack Vector
The attack vector is network-based and targets the HTTP(S) management interface of the router. Exploitation requires high privileges, meaning the attacker must hold an authenticated administrative session or valid credentials. Once authenticated, the attacker issues a crafted request to /router/filter_arp_put_file.cgi with a malformed put_file value. The server responds in a way that discloses out-of-bounds memory to the caller. Additional context is published on VulDB CVE-2026-108906.
No verified proof-of-concept code is reproduced here. See the GitHub Report on ARP Import for the researcher's technical write-up.
Stop Remote Code Execution Before It Runs
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Stop Exploit AttemptsDetection Methods for CVE-2026-108906
Indicators of Compromise
- Repeated or anomalous HTTP POST requests to /router/filter_arp_put_file.cgi from a single source
- Requests containing malformed or oversized put_file parameter values
- Administrative logins from unexpected IP addresses immediately preceding ARP import activity
Detection Strategies
- Inspect router access logs for calls to the filter_arp_put_file_cgi handler outside normal administrative workflows
- Deploy network IDS signatures that flag requests to /router/filter_arp_put_file.cgi with abnormally short, long, or non-ASCII put_file payloads
- Correlate authentication events with CGI invocation to identify abuse of valid administrator credentials
Monitoring Recommendations
- Forward router syslog and HTTP access logs to a centralized logging platform for retention and query
- Alert on bursts of 4xx or 5xx responses from the router management interface, which may indicate fuzzing or exploitation attempts
- Monitor for exposure of the router's management interface to untrusted networks or the public internet
How to Mitigate CVE-2026-108906
Immediate Actions Required
- Restrict access to the router's web management interface to trusted management VLANs or specific administrative hosts
- Rotate administrative credentials and disable any unused administrative accounts on the NR268
- Disable remote WAN-side management if the device exposes it, limiting the attack surface to the LAN
- Audit for signs of unauthorized administrative access since the device was deployed
Patch Information
No vendor patch is available at the time of publication. Netcore did not respond to disclosure outreach. Monitor the VulDB entry for CVE-2026-108906 for updates and consider replacing affected devices if the vendor remains unresponsive.
Workarounds
- Place the NR268 behind a firewall that blocks inbound requests to /router/filter_arp_put_file.cgi from untrusted networks
- Enforce strong, unique administrative passwords and multi-factor authentication where supported to raise the bar for the privileged attacker required by this flaw
- Segment the router's management plane from user networks to prevent lateral access to the CGI endpoint
- Where feasible, migrate to a supported router model with an active security response process
# Example iptables rule to restrict router management access to a trusted subnet
iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
